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Color Management Basics

Color management can be described as a set of simple rules that collectively control and maintain consistency in the proofing process. There are three major components to this proofing process which begins at the point of digital capture and ends when we put the image on paper.

  • Calibrating devices
  • Colorspace information
  • ICC profiling and Softproofing

Calibrating Devices

All professional labs utilize specialized tools to measure and calibrate the devices that collectively make up the digital imaging chain. Each device can be thought of as a link in this chain and include things like scanners, monitors and printers. Calibration devices simply measure each devices ability to display light and colors.

For example, using a colorimeter one would measure the ability to display color ranges, brightness, and contrast for a given monitor, and ultimately create a monitor or display profile that we would then associate with the device.

Doing so would ensure that as we work in color, we are viewing as accurately as possible the true colors and tonal gradations present in an image.

There are two helpful and relatively inexpensive ways to color-manage. Pantone offers an inexpensive calibration device called the Huey which I believe retails for somewhere around $100. While not as sophisticated as an X-Rite Optix, it is still a worthy piece of equipment for a lot less money that will at least put you on the right path. If you just don't want to purchase a calibration device, there are two simple changes you can make to at least control how you view colors onscreen - brightness and color temp. LCD monitors by default are brighter than they should be and it's important to bring the levels down to around 60-70%. Color temp on monitors is generally set to 9300k which is a pleasing cool white temp. That temp tends to make things brighter and with bluer undertones on screen. The problem is that it is not an accurate reflection of how things look in natural daylight. Changing your monitors temp to 6500K will more closely replicate natural daylight conditions.

Colorspace Information

Color space is a set of numeric values that describe the ability to display a range of colors. Since devices differ in their ability to show colors it's important to know their limitations. Monitors for example, have a limited range of colors they can display while printers can generally show a much wider color range. There are two basic types or modes of color; RGB and CMYK.

RGB is an additive color space meaning it uses and mixes light to create colors. It is also the colorspace used by monitors and display devices. RGB assigns and stores values of red, green and blue in individual channels.

CMYK is a subtractive color space and is used for printers. It describes what colors of ink are necessary so that light reflected off the inks and paper create the colors that we see.

We will begin with RGB as that is where you be operating primarily

sRGB is a color space that was created specifically for monitors or display devices. It is very commonly used, and in truth is perfectly fine for most people. In fact, and because, web browsers are not color managed when displaying images on the web, it should be the color space you use to accurately show colors on the web.

Adobe(1998) is another fairly common color space used primarily by graphics professionals because it has a wider color gamut meaning it can show a broader range of colors. I'll be illustrating this visually for you in a minute.

Whichever color space profile you choose to work from is up to you. What is important is that you properly record this information with all your images so that the next link in the imaging chain knows what to do with the color information in your image.This can be done in any image editing application, like Photoshop, by saving or recording the color space information.

Select "save as" from the file menu and look down to the part of the dialogue box called color. There should be a line entitled ICC profile and a check box next to it.

It just so happens that this particular image had sRGB assigned to it and we're now making sure that this information is saved in the image.

Setting up your own custom workspace in Photoshop

By selecting edit > color settings - we pull up a dialogue box or palette that allows to specify several things.

First you'll notice that in settings I've got Aleks Workspace. This is a custom workspace that I created previously and use as part of my everyday workflow. The next section called working spaces contains the color space information for each mode that I may be working in.

For the purposes of this discussion we really only care about RGB, but you can see that I've got a selection for each category. My default color space happens to be Adobe (1998), and I've spelled it out here. This means that every time I create a new image in Photoshop I will be doing so in this color space.

Next, we see color management policies. This part is important. You can see that I've chosen to always preserve the embedded profile for each mode. This means that when you open an image whatever information is locked up in the image will be preserved and faithfully reproduced.

And finally the check boxes below this spell out what to do when a profile is missing from an image or does not match the default color space. I would recommend that you always tell Photoshop to prompt you in these situations.

For example, if an image you are trying to view does not contain a profile you would want to know that in advance and take steps to make sure you apply the correct the color space before saving.

ICC Profiling and Softproofing

ICC (International Color Consortium) Profiles describe the color attributes of a particular device or viewing requirement. As we mentioned above, they can describe the characteristics of a display device. However what I really want to talk about now is profiling for output devices or printers.

Have you ever tried to print pictures to your printer at home and wondered why the colors were all wrong? Well, the reasons can vary, but ultimately the problem most likely occurred because there simply wasn't any information about both the device you were printing to or the paper you were printing on. This is where ICC Profiles come in and are the final link in the color management chain.

Using another calibration device called a Spectrophotometer, we can measure a printers ability to display color and contrast to a given type of media. Once measured, we simply save the information to a profile which would then be used every time a print is sent to that particular printer and paper. Here is what it looks like:

You can see in this picture that we have a ton of little color squares or targets that we've printed on the particular media we're profiling. Once they are printed we simply measure them with the spectrophotometer to give us values for each color. These values are stored in the new ICC Color Profile which will be created once we're done measuring.

This measurement is done because printers and the paper that you print to vary widely in their ability to show color and gradations. For example, inexpensive matte poster paper generally has the ability to show a decent amount of tonal range but lacks the color punch and Dmax (the ability to show black blacks and shadow detail) of a coated photo paper. Likewise, we would need to build a profile that spells this out specifically.

Here is a visual representation of color space or profiles:

This screenshot is of a color mapping software application that shows the ranges of a particular color space or profile. We can see that Adobe (1998) has a larger gamut or range of color than sRGB. There is also an output profile to illustrate how this paper can handle the colors that we see on screen. The paper profile is of premium photo luster.

SoftProofing

Softproofing is simply a way to take a an ICC profile for a particular type of media that you wish to print to and apply it visually in Photoshop to get an approximation of what the print will look like.

This proofing relies on the numeric values for light and color previously measured, and applies them to the image, allowing you to preview what areas of the image could be affected by the limitations of the paper and printer.