Color Management to the Rescue

This is why color management is needed. It's designed to deal with all these variations among devices (monitors, scanners, printers, cameras, and so on). All we have to do is measure the exact color of red, green, and blue that your scanner and monitor use and also measure which shades of CMY that your printer uses (I'm ignoring the K in CMYK because black ink won't shift the color of things). Then Photoshop can use its wizardry to send different information to each device to compensate for its unique qualities in an attempt to get consistent results on all those devices.

There is one more issue to deal with before we figure out how to get all this stuff to work in our favor. Remember when I said that your eyes see white light when a balanced amount of red, green, and blue light enters your eye? Well, you don't end up with white when you use a balanced amount of RGB or CMY on your monitor, printer, or scanner. Remember that all your equipment uses slightly different shades of RGB or CMY (just like those felt-tip pens), which means that equal amounts of red, green, and blue would produce slightly different results on each device. So balanced RGB on one device might look a little greenish or bluish instead of looking gray. That can cause a lot of problems because many of Photoshop's features (such as color correction) make the assumption that equal amounts of R, G, and B produce no color at all.

The solution to that problem is to make your images out of idealized shades of red, green, and blue that have nothing to do with your monitor, scanner, or printer. We do that partially because the monitor you use to view your image isn't capable of accurately displaying what 100% cyan ink looks like and your printer isn't capable of reproducing the deepest blue that you can see on screen, so you don't want your images to have the same limitations as those devices. This special set of RGB colors is what all our images will be made from; then Photoshop will go to work to make sure it can print and display things correctly using the less-than-ideal colors of RGB or CMY used by our monitor and printers (Figure 7.9).