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 MATTER
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.

THE COLOR SPACES
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.

THE COLOR SETTINGS DIALOG
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.

HONORING A TAGGED FILE
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.

FALSE PROFILES — INSTANT IMAGE ADJUSTMENT
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.

ASSIGN PROFILE — ESSENTIAL FIRST STEP
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!

 CONVERT TO PROFILE
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.

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