Monday, December 20, 2010

Red & gray Ford tractor in landscape overpainting; oil on panel by Paul Baldassini

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“Knowledge speaks, but wisdom listens.”  — Jimi Hendrix

After several more sessions this past week, I’m on the home stretch. Below is the painting to date, another 18 hours or so of work. It’s a relief and great fun to use the larger brushes and loosen up on the background foliage before getting back into the “small brush” stuff with the wheels and tires, but I really dig the whole thing. Just love mixing colors and getting the values right. I started by “oiling up” the entire background with my usual green, a medium-dark mixture of Williamsburg Indigo and Sennelier Chinese Orange mixed with a generous amount of jelly medium Old Master’s Maroger Flemish Medium). After getting another cup of hot coffee, the surface is tacky and ready to accept brushwork using the base green neutralized with Sennelier Warm Grey and modulated with either Viridian, Williamsburg Perylene Crimson or Rembrandt Cad. Yellow Medium. I paint fast and try not to intellectualize to much about what I’m doing or I’m lost and mess things up. It’s important to get it down in one take, directly painted with no looking back. At this point I hardly refer to reference image and just pay attention to my underpainting value map. As usual, the work progresses from the top down and left to right on a particular area. The work progresses in 4 hour bursts — once I get in the zone the time goes by very fast.

Next onto the wheels and tires. My blacks are mixed from Indigo, Perylene Crimson and Burnt Sienna Dark.  Makes a nice rich black and is easily modulated warm or cool with the addition of more or less of one of those colors.  Sometimes I add Ultramarine or Raw Sienna but I never really know when or why, and just try it and see if it works with the overall harmony of convincing outdoor light of the painting.

The first oil up is the aforementioned black but thinned with a lot of jelly medium. Although it’s dark I can still see through to the monotone value map underpainting.  After this sets up, I begin laying in the more opaque body color and blending the forms in light. The final touches are the lighter tones mixed with the addition of Warm Grey and then the highlights mixed with Ultramarine and/or Indigo, Warm Grey and a touch of white.

It all moves very quickly and then I’m onto the wheels, the colors of which are mixed from lots of Warm Grey, Viridian and darkened with Perylene Crimson and/or Raw Sienna.  Highlights are mixed from white with a touch of Warm Grey and  Viridian.

I block in and then refine the red hubs and with carefully and quickly placed smallish strokes of many different values and hues paint the lug nuts and other details. I stop when I feel that I’ve successfully created the illusion of wheels and tires and their attendant details.  Here's a close-up of the wheels in-progress:

To get into painting zone for these sessions I listened to a bunch of stuff including Jerry Lee Lewis London Sessions, recorded in 1973 and featuring a huge group of guest artists including Albert Lee, Alvin Lee, Rory Gallagher, Kenney Lovelace and Klaus Voormann; “Getting To This” from Mick Abrahm’s band Blodwyn Pig recorded in 1970, and the B-52’s immaculately produced “Whammy” recorded in 1983.

Thanks for visiting. I welcome your comments or please ask me a question, I’ll do my best to answer it right away.


Wednesday, December 8, 2010

Red & gray Ford tractor in landscape overpainting; oil on panel by Paul Baldassini

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“The errors of the great mind exceed in number those of the less vigorous one.”  — William Stanley Jevons

After a month-long hiatus from painting because of graphic design and photo restoration “day job” commitments, I have finally settled back into painting mode.

Here is the first stage of overpainting, about 22 hours or so of work so far. I jumped right into the “small brush” stuff as I wanted to get that out the way first. Although most of this stage of overpainting appears to be “red”, in fact I used my standard full palette of colors. The “mother” red was Williamsburg Fanchon (Napthol) Red. That was darkened it with Williamsburg Perylene Crimson and lightened it, depending on the light, with either Sennelier Chinese Orange, Rembrandt Cad. Yellow Medium and/or Sennelier Warm Grey. When I came back and hit the highlights the next day I used Gamblin Titanium/Zinc White and a touch of either Williamsburg Viridian or Indigo. The blacks are a mixture of Indigo and Perylene Crimson modulated and warmed as necessary with Blockx Burnt Sienna Deep. Makes a very rich deep transparent black darker than any tube black and much more interesting to look at.

Work progresses from the top down and left to right on a particular area. The overpainting is directly painted “alla prima” and I try my best not to go back and noodle over an area. I don’t at all mind the seemingly unpolished look of direct painting brushwork — it’s me at work and those are my marks. I work fast and mix and apply color from the gut, sort of an unconsciously planned orderly randomness of marks including occasional wet blending and suggestions of detail. I tend to work in 4 hour “bursts” and once I get in the zone the time goes by very fast.  Here's a detail of my brushwork.

My working method is to mix up a dark thin half-paste of a particular dark value with some medium (Old Master’s Maroger Flemish Medium) and apply it over a section. Although it’s dark I can still see through to my underpainting which is basically a monotone value map. All of my value mixtures are mapped to the underpainting. So then, the darks of the underpainting get darker and, obviously, so does everything else. But that’s OK, because then I come right back over it with paint and no medium. I lay in the mid- and quarter-tones with opaque color where appropriate to establish the light and form. Thus, the shadows, remain thin and translucent and look very natural. There is also a very nice dynamic of thick/thin and transparent/opaque for visual interest.

When done I let everything set-up overnight — on panels the paint stays wet-to-tacky overnight. This is perfect for accepting highlights so I add those right away without any medium using Gamblin Titanium/Zinc White and a speck of either Williamsburg Viridian or Indigo. I can also darken down an area with a darker value mixture a bit of medium as necessary, but I try and keep that to a minimum. Some of the midtone local color was hit with straight out-of-the-tube Fanchon Red.

For these painting sessions I listened to a variety of music including Procol Harum’s “Home” and “Broken Barricades” (both Mobile Fidelity Master Recordings), Talking Heads “More Songs About Buildings And Food”, and The Stooges self-titled first (and best) album, produced by John Cale in 1969. Love that tune “No Fun.”

Thanks for visiting. Please let me know what you think or ask me a question, I’ll do my best to answer it right away.


Wednesday, December 1, 2010

Curves & Auto Curves Image Adjustments by Paul Baldassini

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Greetings everyone! It's been over a month since I've posted as I have been very busy with my graphic design and photo restoration "day job" work. It's quiet again so I'm back to painting and writing for my Blog. My newest painting is also moving right along and I will be posting in-progress updates on this Blog very soon.

Meanwhile, here is Part 3 of my Image Adjustment series, Curves & Auto Curves — actually just the first page is posted below — it's way too much to put up on this Blog. You can download the whole Curves Studio Notes from my website — along with all the Studio Notes — which are  available as .pdfs on the RESOURCES pages. Click this link to get there fast:

Curves & Auto Curves
All images can be significantly improved by performing three simple and painless adjustments: Shadow Highlight, followed by Curves, followed by Sharpening, preferably in that order. The Shadow Highlight adjustment was already discussed in detail in a previous post/.pdf, and this discussion is about using Curves to adjust the tonal range of an image.

Much has been written about image adjustments using Curves, and along with Levels, they are Photoshops most powerful tools for controlling the tonal range of an image. Levels are much easier to learn and use and do an adequate job of improving images, but Curves are more powerful. For years I used only  CMYK Curves (and occasionally RGB Curves) to adjust the tonal range of an image since I was preparing images for use in print media only. I adjusted the curve for each individual channel and produced images that would reproduce well in print. I made sure that shadows would not plug up, that there would be some tone in the highlights (except for specular highlights) and that the mid-tones were neutral to compensate for colorcasts. If I were to describe in detail here how all of that is accomplished and theory behind it all, then this little discussion would soon become a little book and you would most likely not make it past the first couple of pages. If you are interested in that kind of knowledge than I highly recommend reading books such as Professional Photoshop, Makeready, or Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace by Dan Margulis; Real World Photoshop or other books by Bruce Fraser; Photoshop Color Correction by Michael Kieran; or Adobe Photoshop for Photographers by Michael Evening. Online, a Google query of something like “using Curves in Photoshop” will result in a great many interesting and informative hits.

My posts are directed towards artists trying to get the most out of their digital images for use as quality source material for paintings. These reference materials may or may not be in addition to sketches, plein air field studies, or memory. But whatever the reason, the mostly likely end use is probably going to be either an acceptable inkjet print mounted next to your canvas for easy viewing or an on-screen image, or more often, both.

I use the Curves tool in two different ways, one a bit more involved than the other but both perform a necessary improvement to digital images. To access the  Curves dialog press Command-M (think Modify) and you will be presented with the Curves default dialog. If you have been using   Levels up to now, the major difference between the two is that although both adjustments let you adjust the entire tonal range of an image, Levels uses only three adjustments (white point, black point, gamma/brightness), whereas   Curves allows for multiple adjustment points throughout an image's tonal range from shadows to highlights. Many points can be plotted on a curve, but it’s the   Shadow, Highlight and  Midtone points that are the most important to learn how to use. Although it’s more complicated (and very confusing if you’re new to adjusting images this way) you can also use Curves to make precise adjustments to individual color channels in an image. And, like other image adjustments, the settings made in the Curves dialog box can be saved and loaded to apply to other images.

Photoshop Curves Dialog showing location of Highlight, Midtone & Shadow Points.  Highlighted settings at right need to be changed from default settings.

To adjust the tonal range of an image you need to click on and move a point on the Curve. The default state of the Curves dialog contains two endpoints — you have to click to add other points such as a midtone point. So, for example, if you want to adjust the Shadow point, you would click on that point and move it manually or by tapping one of the 4 keyboard arrows, which allows for very precise positioning of the points. Moving a point upward and/or to the left lightens a particular range of tones, and moving a point downward and/or to the right darkens a particular range of tones. Thus, to lighten the shadows, move up a point near the bottom of the curve; if you want to darken the highlights, move down a point near the top of the curve.

Changing the shape of the curve alters the tonality and color of an image. Bowing the curve upward lightens an image, and bowing the curve downward darkens it. Steepen the curve (move the Shadow point to the left) and you increase the image contrast; lower or flatten the curve (raise the highlight point) and the contrast will decrease and the tonality will flatten.

Curves can have different shapes, the two most common being the  “Z” Curve or the  “S” Curve. The simplest Curve adjustment is the   Z-curve which acts much like the  Levels Adjustment in that only the darkest shadows and lightest highlights are adjusted (the top and bottom points moved left or right respectively) making for a “punchier” image with increased overall contrast. The midtones remain unchanged. And often this just is enough to improve the image from its original settings.

By adding additional points (usually not more than one or two, but up to 14 are possible) somewhere on the default 45° curve and moving them up or down, an   S-curve is created. This typically adds contrast to the midtones, since that is normally where images will need improvement, and suppresses detail in the shadows and highlights. All images have to be assessed for their unique characteristics and “deficiencies” so that an appropriate curve can be built. There's no precise formula to follow, and the exact appearance of the curve will depend on the content of your image.

Go to  for the complete Curves & Auto Curves Studio Notes.

Tuesday, November 9, 2010

Red & gray Ford tractor in landscape underpainting; oil on panel by Paul Baldassini

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“Suggestion is much more interesting than statement”  — Noel Coward

Here is the completed underpainting, in Quinacridone Magenta (Sennelier) oil on 1/2-inch MDF panel, sealed and primed with one coat of Latex exterior white housepaint and two coats of Gamblin Oil Painting Ground. Trim size is 33 1/2 x 24 inches.

I continued working my way down, pickle jar full of OMS, a big glob of Quin Magenta on my palette, and a rag in my left hand. I thinned out the paint as necessary laying in tone and wiping out, much like the way I would paint a watercolor. After all of the up close detail work with smaller brushes, it was fun to work the foreground grasses nice and loose using a larger brush and holding it way back at the end of the handle. Total time was about 8 hours. I’ll start the overpainting next and as long I stay true to the values of the underpainting with my color mixing, there should be no problems. But before I start that the underpainting needs to dry for a several days, at the very least.

For this last painting session I listened to more of the Fleetwood Mac  Live at the Boston Tea Party   3-CD set recorded in February 1970 as well as Lou Reed’s   Live in Italy  recorded during the 1983 tour. Great band on that tour btw, featuring Robert Quine’s psychotic lead guitar.

Thanks again for visiting.


Wednesday, November 3, 2010

Red & gray Ford tractor in landscape underpainting; oil on panel by Paul Baldassini

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“Few people who do anything excellent are ever heard of...Americans have been bred to appreciate the success of the mediocre.”  — Frank Zappa

With my composition laid out, today I began the underpainting, again using Quinacridone Magenta (Sennelier) straight out of the tube. This time around I’m painting on a primed panel instead of my usual linen mounted on panel. The panel is 1/2-inch MDF sealed and primed with one coat of Latex exterior white housepaint and two coats of Gamblin Oil Painting Ground, which is a mixture of alkyd resin, titanium dioxide and barium sulfate — no lead. Trim size is 33 1/2 x 24 inches.

Painting on this surface is different from painting on the primed linen. It’s more slippery as the paint sits on top longer before sinking in so the underpainting takes longer to dry. That's OK with me because by thinning out the paint with OMS I can make the paint behave much like a watercolor. Areas can be totally removed as necessary with a brush dipped in pure OMS or blended together drybrush. Over the course of the painting session the paint stays wet enough to easily manipulate including glazing over with darker paint or wiping out with a rag or brush or both. I keep a couple of folded up sheets of paper towels on the end of my palette to blot up excess OMS from the brush as necessary to effect the area I’m working on. Likewise, if I were working on a watercolor I would use a small household sponge to wick water off my brush as necessary. It’s very easy to make corrections and entire sections can be wiped clean to start over without disturbing the underlying disegno (I love that word). I start at the top and noodle and muddle my way down so my hand does not rest on wet paint when getting in close for some detail work and/or I use my trusty mahlstick. It’s a nice way to paint and exciting to watch the composition take shape and emerge from the pure white ground.

The tunes for this session came from Frank Zappa’s 1970  Burnt Weeny Sandwich  (the 1983 remastered version) featuring most of the original Mothers, and Fleetwood Mac  Live at the Boston Tea Party   recorded in February 1970, part of a superbly produced triple CD package remixed and released in June 1998 featuring founder Peter Green in a sublime performance.

It will be another day or two until I get to Stage 2 and completion of the underpainting so please check in then.


Tuesday, November 2, 2010

Red & gray Ford tractor in landscape disegno; oil on panel by Paul Baldassini

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“Art produces ugly things which frequently become more beautiful with time. Fashion, on the other hand, produces beautiful things which always become ugly with time.”  — Jean Cocteau

This past weekend I began work on a new painting. The source image was composited from two separate images. One was of an immaculately restored 50's era red and gray Ford 8N tractor. The other was a shot taken at local farm around the same time of day and with similar lighting conditions. The compositing was done in the same manner as described in an earlier post, my usual technique for developing compositions with silhouetted objects and replacement backgrounds. Standard stuff I learned from years of advertising product retouching and compositing. I still do a lot of it — have to pay the bills, making art certainly doesn’t.

My prep work normally takes about 3 - 4 hours depending on the amount of detail. This one required a lot of patience as there was quite a bit of detail that needed to be recorded. It’s the single most important part of my process and I listen to music and take my time — the success of the painting depends on this road map.

I decided to paint on a primed panel this time instead of my usual linen mounted on panel. No particular reason, just to break the routine and try something different. The panel is 1/2-inch MDF sealed and primed with one coat of Latex exterior white housepaint and two coats of Gamblin Oil Painting Ground, which is a mixture of alkyd resin, titanium dioxide and barium sulfate — no lead. Needs about two weeks to dry thoroughly, maybe less if baked in the sun 6-8 hours. Trim size is 33 1/2 x 24 inches.

I listened to a variety of tunes while I did the layout: Frank Zappa’s Sleep Dirt from 1979 — incredible close-miked studio acoustic and electric sessions; The Allman Brothers Band Fillmore Concerts recorded live at Bill Graham’s Filmore East, March and June 1971; and John Mayall’s USA Union from 1970.

Stage 1 of the underpainting will commence right away so please check in again soon.

btw: disegno  (pronounced dee-se-nyaw)  is Italian for “drawing.”


Friday, October 29, 2010

Paul Baldassini Studio Notes now available as .pdf files

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Hello everyone! I've taken a short hiatus from painting and have spent most of the past two weeks on major updates to my fine art website. All of my Studio Notes are now available as downloadable .pdfs on my website on a new RESOURCES page. Click this link to get there fast:

I also posted a listing of some great artist and art related websites worth visiting  including suppliers, discussion forums and technical info sites. My newest painting is featured on my splash page as well as the updated Working Land gallery of current paintings. Please visit and have look.

Very soon I'll begin posting in-progress development of a new painting on this Blog again in addition to new  Photoshop Studio Notes.

Thanks for visiting!


Thursday, October 21, 2010

Grayscale conversion of color images by Paul Baldassini

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Conversion to grayscale

In keeping with recent Studio Notes, I am republishing this post with some minor edits and as a stand-alone Photoshop Studio Note.  This Studio Note and all previous ones will soon be available as downloadable .pdfs on my next website update which include a new page RESOURCES.

After over 30 years as professional graphic artist, I have grown quite used to using image editing software -- mainly Adobe Photoshop -- to develop my compositions.  I am very comfortable with this way of working even though I sketch and draw often, usually at cafe’s. My compositions are initially developed using the viewscreen on the back of my digital camera (I use a Canon G10, an incredible little machine for under $400) and then the images are assessed for usability in Photoshop.  I use both Auto and Program mode, Auto for a moving subject like a farmer on a tractor for example and Program mode for stationery objects, like hayrolls or a tractor idle in a field. This requires a VERY steady hand but produces fantastic source material for paintings.  I will elaborate on this technique in a future Blog posting.

Nothing beats a grayscale image for checking values so I always create a grayscale version of my completed composition as visual reference to check values while painting both the underpainting and overpainting. There are many ways to do things in Photoshop, but the easy way is often not the best way.  Going to MODE >Grayscale and converting from RGB to Grayscale almost always produces a muddy, flat and dead looking image.  And this may be fine for most people, but I use my grayscale conversions for a lot more than just checking values.

First, I can use the data stored in each of the 3 channels (assuming RGB color mode) to significantly improve the tonality and contrast of my original image by creating new alpha channels that have been blended from the Red, Green and Blue channels. If you click on each of the 3 channels separately you will notice that each channel is, firstly and most importantly, a grayscale image already.  From the top (Red channel) down each channel gets progressively DARKER. The Blue channel contains all of the bad stuff -- in a portrait for example, the Blue channel contains the pimples, wrinkles, 2-day beard growth, etc. along with all of the noise (grain) present from the original camera settings.  The GREEN channel, however, contains all of the good stuff this channel BY ITSELF, again in the case of a portrait, will produce a MUCH better grayscale image than simply converting the whole image to Grayscale Mode.

There are several ways to do this.  One is to simply click and drag the the Green channel into the little dog-ear icon at bottom left of the Channel palette right next to the little trash can.  This will DUPLICATE the Green channel into a NEW alpha channel named “Green copy”.  You can easily duplicate Layers the same way.  Then go Image >Mode and select >Grayscale.  You will get a dialog “Discard other channels?”  Click OK or hit the ENTER key and you now have a single channel Grayscale image. Go to >File >Save As and name and save your new image.

A better, and more advanced, way if to use one of the two most powerful and overlooked functions in Photoshop -- Calculations and Apply Image.  They live in the >Image drop down as shown in the screen grab here.  Calculations is used for generating new grayscale Alpha channels only and Apply Image is used for effecting real-time changes to the original color image only.  This post will only deal with the Calculations functions.

For this demonstration I will use a portrait as they best illustrate the technique of grayscale channel blending.  The image is of my daughter. The original image is an RGB file as seen here and next to that is a standard grayscale conversion.  Very dull and flat.  After examining the channels it can be clearly seen that although the Red channel image is too light in the facial tones, the Blue sweater has much more detail than in the Green channel.  The facial tones look much better in the Green channel but the sweater is very dark.  I could use the Green only -- I think its better than the converted Grayscale image -- but it can easily be improved by blending, or combining, the best data of both the Red and Green channels.

Left: original RG image; right: standard grayscale conversion

Below is screen grab of the pane and here’s how it works: go to >Image >Calculations and you’ll get a new pane with options to set and change things.  The first one is Source 1 which is the name of your open file. Unless you have another image open the same physical size, this will be you only option here.  Source 1 has two sub-menus: Layer and Channel.  Unless your file has more than one layer, Background will be your only Layer option here.  If you have more than one layer, be sure to set to the layer you want to blend channels from. The second sub-menu is Channel and here is where you choose the first channel you want use to blend.  Choose Red.  Everything repeats again for the next set of options, Source 2 and your only choice here is your open file so leave it alone.  Set Layer to Background or leave it alone also, and then for Channel choose Green.

Calculations drop-down menu and work pane

Next is where you can really make some radical changes to your grayscale image depending on which Blending mode you choose.  Blending modes are the real core of Photoshop’s ability to manipulate images and If you have never worked with Blending Modes before they may seem daunting.  But please try some out here to see what happens and then you can try them out later on your layered files in color, in real time.

For this demonstration I want to combine or ADD some of the Green channel to the Red channel, so from the drop-down Blending menu I cho-se Add, >Opacity 100%, >Offset -20, >Scale 2.

Finally at the bottom, you have another drop-down menu where you can choose what to do with the new channel you just created.  The default is New Channel and most often this is what you should do. The default option adds a new alpha channel to your file and you can do with it what you will.  So just click OK, or hit the Enter Key and you will be now see a NEW 4th channel in the Channel palette named Alpha 1.  Double-click on the type only and name the new channel.  I chose “Red.Green.add.-20%” so I could remember what I did.

To make a NEW standalone file click on the new channel highlighting (a blue tint), then go Image >Mode and select >Grayscale.  You will get a dialog “Discard other channels?”  Click OK or hit the ENTER key and you now have a single channel Grayscale image. Go to >File >Save As and name and save your new image.

The other option is to select >New Document. Click OK, or hit the Enter Key and you will now have a new file automatically in Grayscale mode.  Just save and name the new file.  If you compare the standard Grayscale conversion to the Calculations generated function version you can see the difference, even though that differernce may not be that apparent on your monitor and/or at this resolution.

Left: Red channel; center: Green channel; right: blended Red & Green channel

Below is the same treatment applied to a source image for one next paintings. At top left is the standard Grayscale conversion. The others were generated the same way as in the preceding demonstration.  The main way that I utilize my Grayscale images is to produce a large paper proof same size as my prepared panel.  I use this paper to produce an outline drawing of my composition onto my panel by sandwiching a piece of Sally transfer paper between the proof and the panel. The standard Grayscale conversion would have produced too dark an image for me to see the traceable detail, but the Red channel combined with the Green channel kept all important detail light enough to see and easily trace onto my panel.

Top left: Standard Grayscale conversion; top right Red channel; bottom left:  Green channel; bottom right: blended Red & Green channel

Sounds like a lot of work but its actually quite fast, the variations are unlimited and I find it well worth the effort.  It also opens you up to new creative levels of understanding in Photoshop which can only improve your design and composition choices. I urge you to try many of the Blending Modes, especially on layered images, and change the opacity on some to produce a very different range of possibilities from the original image.

That’s it until my next post.  Thanks for visiting.


Tuesday, October 19, 2010

Receding Hayrolls field study — Paul Baldassini

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Receding Hayrolls
Oil on linen, 14 x 16 inches
$375 unframed, plus shipping

This study was started in the field two years ago. I finally got around to completing it in the studio recently after rearranging the hayrolls to make for a more pleasing composition. Although nature always provides the most spectacular sources for painting inspiration she doesn’t necessarily always cooperate in the design department. So I took liberties and license and after a bit of reworking the layout settled on this composition. A few color adjustments and a glaze to darken the lower foreground made it a keeper.

Monday, October 18, 2010

Image Adjustment Part 2: Shadow/Highlights

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“Creativity is allowing yourself to make mistakes. Art is knowing which ones to keep.”   — Scott Adams

Before the introduction of the  Shadow/Highlight Adjustment  in Photoshop CS in 2003, it took a lot of moves to make an underexposed image usable.  False Profiles  (see Studio Note Assign/Convert Profile) were usually the starting point followed by channel blending and then a healthy dose of Curves. If you worked at it long and hard enough you could salvage almost any image and make the client — and yourself — very happy. No need to reshoot or start from scratch or wonder when you’ll ever catch that great sunset again.

Those days, for the most part, are long gone although I still regularly use channel blending, occasionally  False Profiles  and always use  Curves  to adjust images. Thanks to the  Shadow/Highlight Adjustment (SHH)  command complex image manipulations are performed in the background using a simple front end dialog for getting the job done quickly. The Shadow/Highlight command quickly became a favorite with photographers, photo retouchers (like me) and pre-press professional for its amazing ability to bring out details in the shadow and highlight areas of an image that were too dark or too light to see. In fact, the Shadow/Highlight command is so good at bringing out image detail that I apply it to just about all of my images, even those that at first glance don’t seem to need it.

Shadow/Highlight  is only available as a standard image adjustment, not an  Adjustment Layer.  Standard image adjustments are permanent so its a good idea to to protect the original image. So before doing anything (and you should ALWAYS do this first before working on ANY image) duplicate the original image by click-dragging the  Background Layer  onto the little dog-eared icon at the bottom right of the  Layers Palette. You now have new layer named by default  Background Copy.  Double-click the name Background Copy. It will turn a light blue color and you can type a new name right over it. I usually name the layer add  SHH at the end.

Photoshop Layers Palette. The New/Duplicate Layer icon is circled in red.

Now open the  Shadow/Highlight Adjustment  window by going to >Image, >Adjustments, >Shadow/Highlight and you’ll see a window that looks like this:

Photoshop Shadow/Highlight Adjustment default window settings.  They will produce an unsatisfactory adjustment and need to be changed.  Start by checking the Show More Options box.

Shadows  value of 50% is usually way too much to start with and will result an unnaceptable image adjustment. A simple change to the default settings is all that’s necessary to quickly produce a significantly improved image. Start by checking the  Show More Options  dialog and you’ll get an expanded window that looks like this but with default Photoshop default settings instead of my settings that you see here.

Photoshop Shadow/Highlight Adjustment with new values replacing the default settings. These settings will give you a much better starting point for producing a great looking image and you can adjust them as necessary for each image. Click Save As Defaults after resetting the numbers and these settings will be permanent whenever you call up the Shadow/Highlight Adjustment .

The expanded version of the Shadow/Highlight dialog box appears a bit intimidating at first, especially since the simplified version contained only two sliders, but not to worry. The expanded window is divided into three sections — two of the three sections,  Shadow  and  Highlight,  are exactly the same with each group containing three sliders to help bring out shadow or highlight detail in the image. Below the Highlights section is the Adjustments section which offers a few more options for adjusting the image.

The first slider,  Amount,  is straightforward enough. It controls how much you want to open up the shadows, making them appear brighter. After you become more familar with what the various setting do to alter the image you can just punch in the numbers. But for now draging the sliders is the way to go and you’ll see the results on your image in real time as you make your adjustments. Drag the slider towards the right and you’ll recover more shadow detail. Rarely, if ever, will you need to set the amount past 50 as your image will start to look weird and unnatural. start  If you drag it too far, you'll brighten the shadows too much. That’s why I start with a value of 25 — to see how it looks then go up or down as necessary from there. Every photo is different so just keep an eye on your image as you drag the Amount slider and set it to whatever looks good for now.

The next setting is the  Tonal Width  slider. This determines the range of tonal values that will be affected by the adjustment. Lower numbers affect only the darkest areas (values) of the image. Moving the slider to the right will expand the range to include more of the midtone values. There’s no right setting so just experiement to see what looks good for your particular image. A good starting point for  the Tonal Width  setting of 50%.

The last slider in the group is the  Radius  setting which determines how the other two adjustments you just made will blend in with the rest of the photo. A low Radius value will make your image your appear noticeably flat with harsh transition areas between the adjusted and unadjusted areas of the image. I think a higher Radius value works best so start with a value of 90 pixels and adjust up or down from there. After setting the Radius value you may want to go back and re-adjust the first two settings — I often go back and forth several times before I see something I like.

The  Highlights  group works the same way as the  Shadow  group. I tend to go easy on the highlight settings as overall image contrast can easily be compromised so minor changes often help. My new settings are: Amount 6%; Tonal Width value of 50% and a Radius value of 90px. The settings that work best on your image will most likely be different but these settings deliver a good starting point.

The last group,  Adjustments,  help to restore color saturation and midtone contrast that might have been lost after making the new Shadow and Hightlight adjustments. The first slider,  Color Correction,  is not really a color correction at all, but a saturation adjustment.  Move it to the right and the color saturation increases; to the left the color is neutralized. The  Midtone Contrast  slider is used to increase midtone brightness values giving the image a bit more “punch” if desired. Leave the default  Color Correction  alone and setting  Midtone Contrast  value of +6 is a safe start.  Black Clip  and  White Clip  specifies how much of the shadows and highlights will be clipped (reset) to the new Shadow (0) and Highlight (255) colors in the image. Larger values means greater image contrast so don’t set them too high or you’ll be right back where you started, more or less.

Lastly, after resetting the numbers, click  Save As Defaults,  and the new settings become the default settings. Below is an image before and after these new default settings have been applied. Simple, painless and no need to adjust further. At least as far as image  Shadow  and  Highlight  are concerned. Of course, there will always be the need tweak an image further and it will usually be necessary to make a REAL color correction, most likely by applying  Curves,  and then the image will require  sharpening.

Left: Original image from digital camera sRGB default color space.  Right: Same image with Bruce RGB Assign Profile and new Shadow/Highlight Adjustment applied.

That’s for Image Adjustments Studio Notes parts 3 and 4.

See you soon!


Friday, October 15, 2010

Image Adjustment Part 1: Assign/Convert Profile

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“The world proceeds without our permission. It will be hot or cold, rain will fall, trees rustle in the wind.”  — D.T. Suzuki

Colorspace and profiles are an extremely important aspect of how your images are presented onscreen and whether or not they will print correctly.   An image file with an  embedded profile, aka tagged image file,  will let whatever or whoever or you may happen to send your file to the meaning of the RGB or CMYK values. And, hopefully, in the case of the latter, they also understand why its necessary and important to do this, and will “honor” your tagged file, that is, leave it alone and not mess up the numbers.

Applications and devices need to know what   color space they are working with. Most importantly, this includes your  monitor.  Without knowing what color space your monitor displays images in, it is impossible to accurately gauge how your images will appear in print. Calibration and profiling of your monitor — device color space — is the first step towards a color managed workflow. A  device color space  simply describes the range of colors, or  gamut,  that a monitor can display, a camera can see, or a printer can print. A device-dependent color space is tied to the idiosyncrasies of the device it describes. For the sake of keeping this Studio Note a reasonable length, I will not go into great detail about how to calibrate your monitor except to say that you can attempt to do it manually or you can use a third-party hardware and software calibration package to get the job done. Its very important to do this.

My current monitor is self-calibrating using a hardware calibration device and proprietary software. A  color space profile  is generated and placed in the  Profiles Folder,  which is in the  ColorSync folder  which is in the Library folder of my hard drive.  This Profile has a name “CRS Print RGB D6520153275” and is used by Photoshop to reference what all of the color numbers mean and how to display them properly in  device-independent,  editable Color spaces such as  Adobe RGB, ColorMatch  or  sRGB.  They also determine a color range you can work in and their design allows you to edit images in a controlled, consistent manner.

It is the editable color spaces that I want to discuss in-depth here and there are four of them built into Photoshop that you need to become familiar with:  sRGB, ColorMatch, Adobe RGB  and CMYK,  and a fifth one,  Bruce RGB  that I prefer, and requires a simple custom installation, described later on.

sRGB  is the world’s default color space created cooperatively by HP and Microsoft in 1996 for use on monitors, printers, and the Internet. It is the default colorpace in Photoshop’s Color Settings dialog as well as the colorpsace for most most digital cameras and scanners. sRGB serves as a “best guess” for how someone else’s monitor produces color, so it has become the standard color space for displaying images on the internet. Although sRGB results in one of the narrowest gamuts of any working space, sRGB’s  gamut  (the entire range of colors available on a particular device such as a monitor or printer) is still considered broad enough for most color applications. It has a gamma, or brightness, of 2.2. Convert and save your images in  sRGB  color space if they are destined for online viewing.

ColorMatch  is a colorspace that is often used when images are destined for print as images saved in this colorspace convert nicely to CMYK. It has a gamma of 1.8 (lower gamma numbers mean lighter images) so that images displayed in the ColorMatch colorspace appear lighter.

Adobe RGB  is a wide-gamut color space offering highly saturated colors with images appearing bright and lively. Although most monitors can display the vivid and often electric colors of this color space, unfortunately most of the overly saturated colors cannot be reproduced in CMYK printing and only some of the more saturated colors will translate well to inkjet printing. Familiarity and experience in using this color space is essential when working with digital images otherwise you can expect problems and disappointing results when printing from this color space. It has the same 2.2 gamma as sRGB but its “G” chromacity settings are different resulting in more saturated colors.

Bruce RGB  is another wide-gamut colorspace that lies somewhere between ColorMatch and Adobe RGB color-space profiles. It was proposed by Bruce Fraser, co-author of the definitive work on color management for photographers and pre-press professionals — Real World Color Management. Again, it has the same 2.2 gamma as sRGB but its “G” chromacity settings are different resulting in more saturated colors but less so than Adobe RGB. Actually it’s a very nice colorspace and I use it as my “house” colorspace, specified in the  Color Settings Dialog,  which is the next order of business.

Photoshop straight out of the box requires fine tuning of many of it’s default settings. A good place to start is with the  Color Settings dialog.  Call up the dialog — I use an older version of Photoshop (CS) so for me it’s Photoshop >Color Settings; for newer versions it’s at the bottom of the Edit menu. You will see a dialog that looks like this. You can check Advanced if you want to see what’s there, but it’s not necessary and please leave the options there UNCHECKED.

Photoshop Color Settings dialog.  The highlighted areas need to be changed from the default settings to to these settings.  Choose SWOP Coated... for CMYK as I have made a custom profile for my own CMYK conversions.

The next step is to make a  Custom RGB Working Space Profile.  This is also the way to make  False Profiles  which can be used to adjust (usually lighten) an image BEFORE applying any of Photoshop’s image adjustment tools. More on that coming up. Follow these steps to make a Custom RGB setting:

1.  Call up the  Color Settings  main dialog.

2.  Under  Working Spaces  choose  Adobe RGB (1998).
3.  Click same Adobe RGB (1998) and a large menu will pop open. Scroll to the top and choose >  Custom RGB.  You will be presented with the dialog box below. All of the numbers should look like this EXCEPT for the Green Primary values.
4.  Type in a new name —  Bruce RGB,  and at the bottom enter  Green X 0.2800; Green Y 0.6500.

5.  Click OK and you will return to the   Color Settings  main dialog. Click and scroll to the top to “Save RGB”. where you will be prompted where to save your new Profile.

6.  Click OK and you will return to the Color Setting main dialog where you will now see   Bruce RGB  as your new RGB color Working Space.

Photoshop Custom RGB Settings dialog.  The highlighted areas need to be changed from the default settings to to these settings.

Now back to the  Color Settings  main dialog. In the second group,  Color Management Policies,  there are a number of options that determine the default behavior of Photoshop when you convert from one profile to another and whether or not you want certain actions to be taken when you certain things, without asking you. My suggestion is to change all three  Color Management Policies  from OFF to  Preserve Embedded Profiles,  prompting a dialog when a profile mismatch occurs.

In the very first paragraph of this Studio Note I mentione     “honoring” the tagged file. When a file is “tagged” it means that the image file contains an embedded profile — numbers that define the character of the color in an image. Those numbers were of great importance to the originator of the image so an embedded profile should NEVER be deleted or ignored as it remains the only link to the digital source (scanned image, digital photo, original artwork). The embedded profiles can be RGB, LAB, CMYK or grayscale, depending on the working color space selected of the originating person or device. If   Preserve Embedded Profiles  Is turned on then the file will open in the color space as originally intended to be displayed and previewed in. At least that way there is baseline data indicating what the color intentions of the image’s author are. You can always change or override them anyway so might as well honor those intentions by preserving the embedded profile for now, until you become more familiar with  Apply Profile  and  Convert to Profile.  Lastly, YOUR image files should be ALWAYS be tagged so if or when you forward your file along to someone else for whatever reason that, assuming they have read something similar to this Studio Note, they will not screw it up by ignoring your embedded profile, which happens all the time.

Using  False Profiles  to adjust (usually lighten) an overly dark or underexposed original image is a technique established in earlier versions of Photoshop before the introduction of the Exposure command in Photoshop CS2. I still use it all the time to lighten underexposed images and it’s a very elegant way to adjust the saturation of an image without altering luminance. A false profile can easily bring the colors of RGB images that were too brilliant for CMYK back into CMYK print gamut, for example. Making False Profiles is easy. I’ve made lots of them in different Gamma values and in different color spaces. Here’s how:

1.  Call up the  Color Settings  main dialog.

2. Under  Working Spaces  choose  Adobe RGB (1998),  or any other profile you want to modify and save as new profile.

3.  Click same Adobe RGB (1998) and a large menu will pop open. Scroll to the top and choose >  Custom RGB.  You will be presented with the dialog box below. You want to change the  Gamma  value to a LOWER number, resulting is a lighter image appearance.

4. Type in a new name:  Adobe RGB Gamma 1.4

5.  Type in a new Gamma value of   1.4.

6.  Click OK and you will return to the  Color Settings  main dialog. Click and scroll to the top to “Save RGB”. where you will be prompted where to save your new Profile.

7.  Click OK and you will return to the  Color Settings dialog.  Click OK and you’re ready to open an image, assign the new profile and see what happens.

Photoshop Custom RGB Settings dialog.  The highlighted areas need to be changed from the default settings to to these settings.

Repeat to make as many False Profiles as you want. I created Abobe RGB profiles from Gamma 2.1 all the way down to 1.1 (half the original Gamma) which will really lighten up a dark image. If you know where they live in the ColorSync folder you can create a folder — False Profile ƒ — and keep them there in case you want to copy the folder and send them to a friend.

Applying profiles to images can dramatically affect how the numbers are translated into a different color space resulting in washed out or garish colors. This is a bad thing if embedded profiles are ignored and converted to another color space without knowing the author’s intentions, but can also be a  creative aspect of your image editing.  You can easily influence how Photoshop describes and portrays color by assigning various color profiles of the Photoshop working color spaces. It’s an essential first step in any kind of professional or creative image editing.

In the examples below, the image on the left is the original image saved and tagged in Bruce RGB color space. It’s quite underexposed and almost seems unusable, but by simply  assigning  a profile —  Adobe RGB 1.2 Gamma in this example — the image is dramatically altered and is now usable, but still needs work. There are additional tonal and color adjustments to perform yet, of course, but I will cover that in Image Adjustments Parts 2 and 3. Notice how much more detail is now visible in the shadows and mid-tones which were plugged-up and dark. As a painter, I find that shadows add a great deal of interest to a subject, so I like them to appear luminous and with a suggestion of detail, much like in real life.

Left: Original image from digital camera sRGB default color space.  Right: Same image with Adobe RGB 1.2 Gamma Assign Profile — fast and painless image adjustment!

You can assign as many profiles as you want to see how different color spaces will affect the appearance your image. The numbers will not change, only the onscreen appearance.  Please note:  there are other kinds of profiles in your Profile folder, such as print device profiles, scanning profiles, paper profiles and monitor display profiles. I strongly advise against using any of these profiles as they are device specific and NOT color space profiles.
When you’ve decided on something you like then its time to  Convert to Profile.  It’s not mandatory, not something you have to do, and you can leave the file alone just as it is. But I prefer to convert the file (hence the numbers) into my own color space.  Then, you can go ahead and assign profiles again, if you want to, and convert back to your color space when you’re done. RGB to RGB conversions, or RGB to LAB (or LAB to RGB) are all safe and easy ways to perform initial adjustments prior to fine
tuning your image for whatever output it’s destined for.

TIP:  At the bottom left of your image window there is a clickable drop-down menu offering different options. This menu defaults to  Document Size,  but I suggest changing it to  Document Profile  so you always know what color space you’re working in. See the screen grab below.

It’s a good idea to change the default settings to Document Profile.

Lastly, I have purposely stayed away from  CMYK color space  conversions. This color space is best left for images which are ultimately destined for use in print media — conversions to, and working in, CMYK color space warrants a Studio Note of its own. I do however recommend setting your  Color  window to  CMYK Sliders  as it’s more intuitive to specify colors as
percentages of CMYK.  For example, an orange hue might be Y100, M60 but using RGB Sliders would be R228, G145, B36, a bit foreign sounding. I have spent a lifetime in print as a graphic artist so I am very familiar with CMYK conversions, but I do all of my work in RGB. I think you should too.

Sunday, October 10, 2010

Rural CT landscape with tractor in sequence by Paul Baldassini

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Here is a sequential progression of my most recent painting tentatively titled “Orange MMZ in morning light”. A detailed description of each stage can be found in previous Blog posts.

After the painting bakes in the sun for a couple of days, and then dries for a month or so it will receive two coats of Old Masters Mastic Varnish, and then be framed.


Saturday, October 9, 2010

Completed rural CT landscape with tractor by Paul Baldassini

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“The essence of all beautiful art, all great art, is gratitude.”
— Friedrich Nietzsche 

Here is Stage 3, the final overpainting and completed work tentatively titled “Orange MMZ in morning light”. Same palette with fresh paint -- arranged along top edge of my palette from left to right they are: Gamboge Lake Extra (Old Holland); Cadmium Yellow Medium (Rembrandt); Raw Sienna (Williamsburg); Chinese Orange (Sennelier); Fanchon (Napthol) Red (Williamsburg); Perylene Crimson (Williamsburg); Burnt Sienna Deep (Blockx); Viridian (Williamsburg); Ultramarine Blue French (Williamsburg); Indigo (Williamsburg); Warm Grey (Sennelier); Titanium Zinc White (Gamblin). The paints are pretty much arranged warm to cool and lightest to darkest in value.

The bulk of this session included the foreground field and grasses. The base color was a dark mixture of Indigo and Chinese Orange, glazed first with a  halfpaste of jelly medium (Old Masters Maroger, Flemish Formula) corresponding to the overall values of the underpainting. The lighter areas had more medium and less paint with a touch of Raw Sienna added. The glaze was applied with a large brustle brush -- an old Langnickel Series 404, and scrubbed on quickly. While that was setting up I went out and got a cup of coffee. When I returned the glaze coat was already tacky and ready to receive paint.

Indigo and Chinese Orange makes a gorgeous green and is easily modulated into many different green hues by adding more Indigo to cool it down or Chinese Orange or warm it up. To lighten I add Raw Sienna and/or Warm Grey. Then I made up some bright green puddles of Viridian and Cadmium Yellow Medium with a touch of Indigo; Viridian and Chinese Orange; and Raw Sienna, Chinese Orange and Warm Grey.  All the forground values are dark to medium light so NO white is used at all in the mixutres.  Then I just jump right in varying hues but keeping similar values. That makes for very interesting and luminous shadows. The large puddles mutate into smaller puddles and I just grab here and there mixing along the way without really thinking about it. After a couple of hours it looked like a lightstruck field with long cast shadows. I fiddled and diddled a bit until it seemed right then stopped and finished my coffee, now cold.  Below is a shot my palette after todays session showing the little green puddles in a variety of hues and values.

The music I painted by in this session was from a Fleetwood Mac 2-CD compilation “The Vaudville Years of Fleetwood Mac 1968 - 1970”. Released in 1998 on Receiver Records, the package features exquisite previously unissued studio gems “tracing the development of a band firmly rooted in the blues, as it experimented with many different styles of music.” The Madge Sessions on disk 2 is fantastic stuff.

I’ve already begun laying out my next studio work, so please visit again for more in-progress postings.

Thank you.


Thursday, October 7, 2010

Overpainting Stage 2 in-progress of rural CT landscape with tractor

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“An artist paints so that he will have something to look at”
— Barnett Newman

Here is Stage 2 of the overpainting of my newest painting tentatively titled “Orange MMZ in morning light”.  I’m on the home stretch now, only the foreground to complete. My palette remains the same -- arranged along top edge of my palette from left to right they are: Gamboge Lake Extra (Old Holland); Cadmium Yellow Medium (Rembrandt); Raw Sienna (Williamsburg); Chinese Orange (Sennelier); Fanchon (Napthol) Red (Williamsburg); Perylene Crimson (Williamsburg); Burnt Sienna Deep (Blockx); Viridian (Williamsburg); Ultramarine Blue French (Williamsburg); Indigo (Williamsburg); Warm Grey (Sennelier); Titanium Zinc White (Gamblin). The paints are pretty much arranged warm to cool and lightest to darkest in value.

For the most part, I painted the darkest parts of the subject -- the tires and wheels -- almost all of the mixtures for this session were very dark in value. I used mixtures of all of my reds for the wheels, darkening Fanchon Red with Perylene Crimson and lightening it with Cad. Yellow Medium. Hue shifts were accomplished with Chinese Orange.  I try and stay away from introducing any white in the light mixtures as they will become chalky and unnatural looking very quickly.  The darkest darks in the wheels have a speck of Indigo added.

The base color for the tires was a mixture of Indigo, Perylene Crimson and a touch of Burnt Sienna Deep. This combination of colors is my “black” and it is easily modulated in both temperature and value by adding Warm Grey, and/or Ultramarine Blue French. As I paint I “grow” many mixture puddles in a many variety of grays -- warm and cool -- that are biased towards purple, blue and brown. I constantly modulate these values/hues across my forms as they turn towards or away from the light source. This makes for a believable sense volume hence believable reality.

I work each area from dark to light. Each area is glazed first with a medium/dark halfpaste of jelly medium (Old Masters Maroger, Flemish Formula) corresponding to the overall hue of the overpainting.  So for the wheels, for example, I mixed a darkish transparent red from Fanchon Red mixed with Perylene Crimson and scrubbed that over the underpainting. From there I overpaint while the glaze it still wet and getting tacky, up in value using more opaque and thicker body color and highlights, and down in value using transparent dark mixtures. That contrast of thick and thin paint mixtures makes for an interesting surface with believable color with richness in the thin dark tones and shadows. The tires were painted the same way starting with a dark transparent halfpaste glazing mixture of Indigo, Perylene Crimson and a touch of Burnt Sienna Deep.

I love this way of working the paint. As the medium sets and gets tacky you can drag a brush of light valued thicker paint over the darker glaze coat. It grabs the paint and stays where you put it, showing the brushwork or I blend a bit with a dry brush to lose an edge where necessary. It’s important to get into the painting zone where this combination of techniques moves along quickly and unconsciously and without “intellectualizing” the process. If that happens, mistakes will be made necessitating repainting, which I try and avoid at all costs.

After drying overnight, I apply the final highlights thickly here and there, usually pure white tinted with a speck of Cad. Yellow Medium, Gamboge Lake Extra, Indigo or Ultramarine depending on the local color. Occasionally I may have to darken an area with a glaze of jelly medium and some transparent dark mixture. These final embellishments really bring the painting to life.

I always listen to loud music when I paint. Today I listened to (several times over) a rare gem from the Nice entitled same “Nice” issued by Immediate in 1989. Half of the CD is comprised of impeccably produced studio tracks, the other half live at the Fillmore East, NYC, December 1969, also a very high quality mix. There are newer issues with expanded remastered material from that Filmore concert available but I have not as yet had a listen. Rondo 69 is a tour de force featuring keyboardist extraordinaire Keith Emerson (later to form Emerson, Lake & Palmer).  In the Nice’s version of Bob Dylan’s She Belongs to Me .this powerhouse trio really rocks!

Anyway, onto the foreground next -- a variety of the mixed greens from every color on the palette to wrap this painting. Stay tuned!



Wednesday, October 6, 2010

Photoshop and Image Resolution Part 2 -- Print

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“People rush in where angels fear to tread”— Alexander Pope

Vector, raster, grids & dots
Scanning, display and output (even the final printed pieces) all have something in common: they are made up of -- simplistically -- dots. So, the ubiquitous use of “dpi” (dots per inch) seems to be a perfectly correct way of describing all of our resolution needs. Unfortunately its not -- there’s more to it. Lets start with the “dots” we stare at most of the day -- the ones on the monitor.

Scanned images or images created in a digital imaging editing program like Adobe Photoshop are often referred to as raster images, and are distinctly different from the images created in a drawing program, like Adobe Illustrator for example, which are called vector images. Although both are described mathematically as points on a grid, vector images are files whose mathematical basis is predicated on formulas describing lines and curves, and can be enlarged or reduced without affecting their output quality. Thus, vector images are resolution independent,  meaning detail will always appear sharp, scaled to any size and printed to any output device.

The grid points of a raster images, on the other hand, are resolution dependent, meaning that the quality of the image is compromised if enlarged or reduced on any output device. The video display monitor, for example, is an output device made of points (tiny square dots) in a fixed resolution grid. Enlarge the image and you enlarge the grid. Enlarge the grid enough,and you will quickly see the stair-step “jaggies” characteristic of raster images.

The grid points of both raster and vector images are described by numbers, and their mathematics need to be stored. Vector image files, however complex, are smaller than raster image files because the formulas used to create them can be stored compactly. For example, a line can be described mathematically on the grid by identifying its two endpoints only, and those two endpoints will always be in the same place, defining the same detail, relative to the resolution of the grid.

The large file size of a raster image, however, requires that each piece of information on the grid (all of those numbers) have to be stored. More detail requires a finer grid, which means higher resolution and the more points on the grid. That means more numbers, and therefore a larger file.

It’s getting a bit too deep
Zoom out to the maximum in Illustrator, and everything pretty much still looks the same, just bigger. Zoom out to the maximum in Photoshop and you’ll see those grid field points that your image is actually composed of -- lots of small square “dots” called pixels. Each pixel is represented by a particular formula of zeros and ones, commonly referred to as bit depth.

Bit depth as it applies to scanner (input) resolution is easier to understand if you think of it as three-dimensional, whereas imagesetter (output) resolution is only two-dimensional — dependent on the number of dots in the horizontal and vertical directions. Scanners not only have horizontal and vertical directions, but a third one — depth. Even though both scanners and imagesetters describe horizontal and vertical resolution in terms of spi/ppi (samples/pixels per inch) for the former and dpi (dots per inch)  for the latter — depth applies only to scanners or input. It describes the number of bits of grayscale or color information per pixel. Horizontal and vertical resolutions (i.e., scanning at 1,200ppi) are sometimes referred to as spatial resolution, while bit depth is often referred to as tonal resolution. What most people refer to when they use the term resolution, is spatial resolution.

Of bits and bytes
What exactly is in a raster or (bit-mapped) image file? Its those numbers again, and its measured in bits, bytes, kilobytes, megabytes and gigabytes. The smallest piece of information, or data, that can be stored digitally is a bit. It can distinguish only two things (called states): yes or no, black or white, on or off. Just like a light switch. A line art scan would be one bit “deep”and a line art image would be called a 1-bit image, (21) because only one bit is needed to distinguish black from white, like this:

1-bit image
This is why line art file sizes are so small. Grayscale images require more information, hence more bits. Eight bits actually, known as a byte. A 1-bit line art image, measuring 3 x 4 inches , scanned at a spatial resolution of 800ppi (the minimum for line art,) would consume just under one kilobyte (Kb) of disk space (there are 1,024 bytes in a kilobyte.) 

Most grayscale images are eight bits deep; enough to describe 256 levels of gray, considered to be the upper limit of tonal human vision — more than adequate to create the illusion of continuous tone in print. An 8-bit byte can accommodate 256 numeric values, from 0 to 255 because 2 to the 8th power = 256.

Thus, the brightest value of eight binary bits would be the number 255. An 8-bit grayscale image, measuring 3 x 4 inches, scanned at a spatial resolution of 300ppi would weigh in at just over 1,024 kilobytes, which is equal to one megabyte (Mb).

Color images require even more information, and are usually 24 bits deep. A 24-bit color pixel is actually described by the combination of three 8-bit values, one each representing Red, Green, and Blue, and each one having a maximum color value of 255. In Photoshop, the information stored in the Red, Green, and Blue Channels combine together to give us the illusion of color reality that we see onscreen. A 24-bit color image contains enough information to distinguish over 16.7 million different colors (2563 or 224). The file size of 24-bit color images can be quite large — a 24-bit 8 x 10 inch image destined for print media and scanned at a spatial resolution of 300ppi would equal 20.6 megabytes.

There are 1,024 megabytes in a gigabyte (Gb). It would take forty-eight, 24-bit, 8 x 10 inch color images scanned at a spatial resolution of 300ppi to consume that much disk space.

Color by numbers
The data in the image file is organized in columns and rows, like a spreadsheet, or a checkerboard (which always has eight columns and eight rows for a total of 64 squares). The grid of pixels that define the screen of a video monitor might measure 1,280 x 1,024 for a total of 1,236,992 squares.  Thats a lot of squares. These squares or “dots” of a video monitor is simply a data field; our digital image file is an abstract thing -- nothing more than a collection of specific numerical data composed of complex strings of numbers representing the  RGB (Red, Green, Blue) color of every pixel. So then, 255-255-0, or (Red=255, Green=255, Blue=0), would denote one yellow pixel in a screen image, while 45-0-106 would denote a purple pixel, and so on with each image pixel. Nothing more.

Having no real physical size, digital image files become realized ONLY by physical reproduction in some form or another. In other words, the image must be printed (output) to a specified size. Until then, they are nothing more than numbers -- an informational record.  Digital images are usually  printed (output) to a laser or inkjet printer, or an imagesetter. For digital images requiring no physical output, such as those created for use  on world wide web, for example, the output device which your images will be “printed” to is your display monitor.

Display resolution -- no dots, no spots
When scanning or creating images for video monitor display only, resolution merely determines image size. Assuming that greater resolution reveals more detail, it also makes the image larger — much larger that the ability of the output device to display it at 100%. Display screens are just not large enough. Since video monitors are relatively low-resolution devices (typically 70 - 100ppi), to view an image at 100% size and and still fit on the screen means that the scanning resolution or spi (samples per inch) needs to be the same as the monitor resolution. And its NOT 72dpi, a magic number that many seem to think is the set resolution for all video monitors. Better to forget about it.

Video monitors display a fixed area of pixels, such as 1,280 x 1,024, the screen display area of most 17-inch video monitors. It is this “X by Y” number of pixels, like 380 x 260, that matters when describing video image size. And for video, it doesn’t matter that the 380 x 260 image was scanned at 72 or 300ppi — either way, the display area on screen is the same -- but for an image that will be printed, it matters a lot. The same image will appear larger on a 640 x 480 screen than on an 832 x 624 screen, and will look tiny on the 1,600 x 1,200 screen of a high-resolution monitor.

For video (or any other) images, figuring out both the image size and the file size requires some simple math. For example, my Sony Artisan GDM-C520K is set to resolve at 1600 x 1200ppi (pixels per inch). It’s screen display measures 15.5 inches horizontally. So, 1600 ÷ 15.5 = 103ppi (not the usually and wrongly assumed 72ppi of all display monitors). Knowing this then, let’s say we had original color art measuring 4 x 5 inches that required viewing on screen at 100%. Scanning at 103ppi (spatial resolution), with color depth set to 24-bit (8 bits per channel; tonal resolution of “millions of colors”), would create a file whose dimensions (image size) was 412 x 515 (4 x 103 = 412; 5 x 103 = 515) and consume 621Kb (file size) of disk space.

So then, the formula for determining file size is:

(w x h) x bits-per-sample ÷ 8,192 (÷ 1,024 if more than 1Mb) = file size
in pixels       bit-depth            bits/Kb               bits/Mb

412 x 515 = 212,180 x 24 = 5,092,320 ÷ 8,192 = 621Kb

Photoshop Image Size dialog box -- Resolution test

To see this in action just open a new Photoshop document and set the numbers yourself just like in the screen grab above. This file would only be good for posting online. For print media you would need resolution of 300ppi; for inkjet printing you would need resolution of 360ppi. Do the math or plug 360 into the resolution field of the previous test and you get a much larger file weighing in at 7.42Mb.

That’s all there is to it — it really is all in the numbers. And the numbers, at least as far as the scanner and monitor are concerned, are issues of pixels and samples and there are no problems in making an RGB color of any pixel. But other output devices, like laser or inkjet printers and imagesetters, cannot do that and have very sophisticated ways of producing an image. And it’s also about numbers.

The black and white of grayscale
What exactly is grayscale, anyway? One look at a black & white photograph shows that there is little in it that is actually black or white. In fact, most a of photograph’s subject matter contains gray only, of varying shades, which provide both detail and contrast. In general, the more shades of gray in a photograph, the more “realistic” it appears. The “black & white” photography of Edward Weston, Ansel Adams, and Herb Ritts are outstanding examples of continuous-tone grayscale images. A photograph is commonly referred to as a continuous-tone image because of an (almost) unbroken, nearly infinite range of gray tones between black and white.

A printing press, however, can only print one color at a time, so it is unable to directly reproduce a continuous-tone image. Instead, a photograph, or any continuous-tone image, must first be converted into a halftone. Making a halftone is a technique that has been used for centuries by printers to produce the illusion of many shades or tones in an image with only one color. In the case of a grayscale image, that color would be normally be black.

To accomplish this, basically what happens -- or rather what used to happen until sophisticated digital imaging equipment caught up -- is that the photograph is itself “photographed” -- shot through a fine screen, which breaks up the image into a grid of evenly spaced dots (sound familiar?). Varying shades of gray then, are simulated by the variations in the size of these halftone dots. Under magnification, a photographic halftone will reveal dark areas as having many large white dots and lighter areas as having many smaller dark dots. At normal reading distance, however, the dots all blend into the illusion of continuous shades of gray, looking much like the original photograph. The sharpness of a halftone — its resolution — is determined by how closely spaced together those dots are. The spacing of the dots is often referred to as frequency. For example, if the screen through which the photograph was shot consisted of lines of dots spaced at 75 per inch, then the resulting halftone would have a line frequency of 75 lines per inch or 75lpi. In a “traditionally” produced halftone, the nearly continuous gray tones were achieved by varying the sizes of the component dots. But laser printers and imagesetters have fixed resolutions, and cannot produce variable-sized dots. Instead they have a set or fixed grid of equal-sized dots, corresponding to the device’s “resolution”. These dots are, in fact, called spots and the measure of how many of these spots can be made in a linear inch define the addressability of an imagesetter device, and not its resolution, often used interchangeably.

Grids with lots of dots made out of spots
To better understand exactly what you must know and do to create quality images for print requires an explanation of the following terms and concepts:

Imagesetter resolution is a measure of the ability of an imagesetter to render fine detail. Imagesetter resolution is a function of addressability, laser spot size, film transport, film and film processing. The common usage of the term is usually limited to just one portion of this: addressability.

• Addressability is a measure of how many marks (spots) an imagesetter can make in an inch.

• Dot per inch (dpi) is a measure of resolution (addressability). It refers to the number of laser spots in an inch. It has NOTHING to do with scanning or caputure resolution.

• Laser spot is the smallest mark that an imagesetter can make on paper or film. Referred to as spi (spots per inch).

• Spot size is the width of the laser beam in microns, usually measured under a specific set of conditions.

• Screen ruling is a measure of the fineness of a halftone screen. The higher the number, the finer the screen. A common screen ruling used for most sheetfed and web offset printing is 150 lines per inch or 150lpi. This means that there are 150 lines of halftone dots in an inch. The distance from the center of one of these halftone dots to the next would be 1/150 of an inch. Other commonly used screen rulings for offset printing, depending on the characteristics of press and paper, are: 133 or 150lpi, and for newsprint, 85 or 65lpi. A higher screen ruling demands higher resolution.

• Lines per inch (lpi) or line frequency refers to the number of lines of halftone dots in an inch.

• Halftoning is the process used to convert a continuous tone image into a pattern of tiny dots of varying sizes.  The resultant image is referred to as a halftone. These halftone dots create the impression of many shades of gray, but can be reproduced using only one color of ink.

• Halftone dot is used in halftoning to give the impression of gray. Halftone dots of different sizes are used to represent different shades of gray. A digital halftone dot is made up of many laser spots, like this:

Dots, spots, cells and numbers
A fundamental limitation of laser printers stands in the way of producing a halftone in the traditional way: i.e., evenly spaced dots of varying sizes to create the effect of continuous tones. Both laser printers and high-end imagesetters can only make dots of a single size (the size of which varies according to the device’s resolution). These devices “fake” halftone dots of varying sizes by clustering together many laser spots. A laser spot is the smallest mark that an imagemaker can make in an inch, often termed resolution, but more accurately called addressability. The boundary that encloses many of these potential these laser spots represents one halftone dot and is referred to as a cell. Counting all of the potential laser spots within the cell boundary is equal to the number of gray levels that a particular halftone cell is capable of producing.

16 x 16 digital halftone cell showing single laser spot
The 16 x 16 grid shown here, for example, can produce 256 levels of gray (16 x 16 = 256), which is the number of gray levels required to accurately simulate a continuous tone image in print. As we have already seen, the data contained in a digital image is ephemeral, awaiting for us to give it the property of physical size, Thus, an image can always be output as having 256 gray levels and appear tonally correct as any given size on the display screen. But this does not mean that the image is suitable for reproduction at any size.

Actual output image size (dimensions) are inversely proportional to its resolution. For example, a grayscale 4 x 5 inch image to be output to my laser printer at a frequency of 75lpi would require a resolution 150ppi to assure 256 levels of gray. It’s dimensions would be 750 x 600 pixels and  weigh 440Kb. If this image is rescaled in Photoshop to 8 x 10 inches, its resolution would change to 75ppi, but the file size would remain the same (750 x 600 pixels) and still be 440Kb in size. It would look EXACTLY the same on the screen, only the physical dimensions would be different. Thus to produce a full tonal range on my laser printer with a spatial resolution of only 75ppi, the line frequency would have to be an unusually coarse 37.5lpi, useful for silk-screen printing on fabric, perhaps, since detail will be obscured by dot size.

Sharpness and detail (hence quality) of the image is dependent not only on the ability of the input device to sample detail, but also on the ability of the output device to resolve that detail.

Understanding the relationship between both input and output “resolution”, then, is extremely important. It is the first step in the process of acquiring a digital image and can make or break the success of a printed image. If you understand the concepts outlined so far, then you will understand digital halftones and avoid the potential problems in creating them. Posterization, or “banding” of an image, for example is a function of screen ruling, resolution, and the number of grays, and is usually undesirable.

As stated already, the relationship between the screen ruling of an image and the resolution at which the image will be output plays an integral role in image quality.  Fortunately, any value between 100 and 256 levels of gray will usually be enough to produce an acceptable digital image for print, with paper quality often being the overriding determining factor.

The rule of sixteen
I mentioned earlier that the number 16 would show up again and again. 16 x 16 = 256, for example -- the other magic number, and if you multiply 256 x 4, you get one kilobyte. That said, the easiest way to calculate the highest screen ruling to use on any particular output device is simply divide its addressability (resolution) by 16.

For example, the addressability or resolution of my laser printer is 1,200 laser spots per inch -- usually referred to as 1,200dpi. If you divide 1,200 by 16 you get 75. This means that there are seventy-five halftone dot cells per inch, measuring 16 x 16, each cell containing 256 potential laser spots, thus allowing 256 levels of gray. 75lpi is the highest screen frequency available with the greatest levels of gray. My laser printer is physically not able to output at a higher resolution and maintain 256 levels of gray. The device can produce continuous gray tones and high resolution but it can’t do both at the same time.

If, for example, I output my image at 150lpi, the grid would change to 8 x 8 cells, (1,200 ÷ 150 = 8). However, the number of gray levels decreases to only 64. Why? Because a halftone cell dot measuring 8 x 8 contains only 64 potential laser spots, yielding only 64 levels of gray which would result in banding and abrupt transitions in the image.

To output the image at 150lpi and contain 256 gray levels, would require a device capable of producing 150 halftone cells measuring 16 x 16 per inch. That means an imagesetting addressability (resolution) of 2,400dpi (150 x 16 = 2,400).  F.Y.I., laser spots of this addressability are measured in microns. One micron equals .0003937 inch. One point equals 352.78 microns or .0139 in.

The last piece of the puzzle
Now that all the technical stuff is out of the way, you can go ahead and scan with the confidence that your image will contain enough numbers to be the size you want it, at the proper line screen (if your image to be printed), and containing the right amount of tones. There is, however, one last piece to the puzzle.

Exactly how much “resolution” is enough to scan at and/or how much is enough to create original art directly in your favorite painting or imaging program?

There is much debate on this issue, but its safe to say that input resolution (spi) should be at least 1.5x and no more than 2.5x the desired line frequency (lpi). A factor of 2x is the commonly used ratio of spi to lpi; the ratio most used since the advent of “desktop” publishing.

Thus, using the math learned so far, an original piece of art measuring 4 x 5 inches to be printed in color at 100% size at a 150 lpi should be scanned at 300ppi (1,200 x 1,500ppi) with the color depth set to “millions of colors” (24-bit). The math to figure it all out goes like this:

1,200 x 1,500 = 1,800,000 x 24 = 43,200,000 ÷ 8,192 = 5,273.43Kb ÷ 1,024 = 5.15Mb

Which is fine if you plan on only using that image one time at that size and at that line frequency. I find that most images almost always end up being repurposed for something else down the road, and would rather have too much resolution than not enough. So, if you have the disk space, or some archiving hardware, I recommend always scanning at the maximum optical resolution of your scanner.  These days its typically 1,200spi/ppi or higher. And of course, this produces quite a large image file because it contains a lot of numbers.

The same 4 x 5 inch original scanned at 1,200spi/ppi (a typical optical scanning resolution of many of todays scanners) weighs in at just under 83Mb (see screen grab below). But, it would look exactly the same onscreen. Why? Because scanning with all that extra resolution has no effect on the quality of the image at all — it just takes up more space on your hard drive. It doesn’t increase the quality of the image any more than pouring a 16-ounce glass of water into a five-gallon drum will make the water taste better. It would just take up a lot of room in your kitchen.

Photoshop Image Size dialog box -- Resolution test 2
But, since images for print require more resolution to look good than screen images, that 4 x 5 inch image just scanned at 1,200ppi now contains enough data to be output at 300ppi (proper resolution for 150lpi printing), at a size of roughly 14 x 16 inches. To repurpose this overweight image for use at the original size of 4 x 5 inches, however, a lot of data would need to be jettisoned. This is called resampling, in this case, downsampling, covered in depth in a previous post. Whenever an image is resampled, its integrity is severely compromised — if the original was sharp and detailed to begin with, after resampling it will now appear blurred when viewed onscreen at 100%. Sharpness, hence detail, needs to be restored.

That’s a story for another day.

Thanks again for listening.