It is time for us to take a little detour on our way to the Grand Canyon, and talk a little bit about color management. We often hear the sentiment expressed by the blog title when people get their photos back or try to display them on a different device than the one they worked on at home. Color Management covers a great deal of territory, so this blog will just cover some critical details. There are volumes and tomes about the intricacies of this subject and they can make your head spin. All of us want our images to look the way we envision them no matter the format or medium.
One of hardest issues to wrestle with is the fact that none of us truly know how something looks to any other person on the planet. There are people who suffer from color blindness and others whose astigmatism changes their perception of pure black into shades of gray—not 50 perhaps, but who knows? Those factors are out of our control; but trust me, there are lots of knobs and sliders for us to work with. We have to establish a common language to describe colors.
There are mathematical models which can tell you what wavelength the color red is—700-635 nanometers, but that doesn’t really help in fixing an image. The human eye operates between ~400 and 700 nm but, unfortunately, our electronic devices such as printers and monitors can’t accurately reproduce all of the potential color combinations. A key term we need to know is GAMUT. It is the specific subset of colors which can be displayed.
The next key concept we need to know is COLOR SPACE. A color space is a common set of standards that define a specific Gamut and which can describe a particular color. In photography, we commonly use three of these: CMYK, L.A.B., and RGB.
CMYK is the most common for professional printing jobs. Cyan, Magenta, Yellow and Black are combined to create rich deep colors.
L.A.B. takes a completely different approach. As shown in the picture, you have an a channel which starts at green and goes towards the magenta. The b channel goes from blue to yellow. A separate Lightness channel describes how far out from the black center a specific color sits. L.A.B. can be very powerful in color correction, but is not the focus of this blog.
We normally work in the RGB color space. Red, Green and Blue colors are mixed together to form all of the remaining colors.
Unfortunately, RGB does not cover all of the colors that we can see. There are two common RGB formats we need to understand: Adobe RGB 1998 and sRGB. sRGB is actually the format used by most electronics. It covers about 35% of visible color. Adobe RGB covers about 50% and more closely maps to the color range available in CMYK printers.
Amazingly, at best, we are currently able to reproduce only half of the colors our eyes and brains can see. As technology increases, other formats such as Pro Photo RGB are gaining ground.
Whew, that is a lot of stuff to take in and we have not even started talking about how we can manage our work. I guess that will have to wait until next week.