Color Management Primer

When Four Equals Six

Ever since the first images were displayed on computer screens and then printed on paper, there has been a need for color management. The behavior of "color as light" (which is how images go from the computer screen to our eyes, as a mixture of Red, Green, and Blue light) is rather different from the behavior of "color as a material" (which is how images are printed on paper, as a mixture of Cyan, Magenta, Yellow, and Black pigments or dyes).

A commonly referred to analogy for color management is toasting bread. Imagine you have a loaf of bread. You put one slice in your home toaster and toast it at a setting of "4" and you are happy with the results. You then go to a friend's house and you want to know what setting to use on their toaster. One (admittedly tedious) solution is to take 10 slices of bread and toast each of them at a different setting and then figure out what setting on your friend's toaster matches your setting of 4 at home. Let's say on your friend's toaster you need a setting of "6" in order to get the same results as "4" on your home toaster. What you have just done is created a profile for toasting bread. One basic way to think of profiles is that they are "lookup tables" which are used to convert from one device to another.

Here is another example that relates more to digital imaging and digital printmaking: Let's say you have a piece of grey paper, and on a scale of 1 to 10, this grey is about a "4". If you scan this grey paper, and then print it out on a printer, it might print out at a level of "6". You now have a profile, or lookup table, for this paper. In this case, you know that from scanner to printer, a "4" equals a "6", and you can probably guess that scanning a "2" will yield a "4" on the printer. This is a very basic example, but the concept is directly applicable to Color Management: creating profiles (lookup tables) for all the devices in your digital workflow. Most every device that displays or captures color can be profiled. This includes Monitors, Scanners, Printers, and even Digital Cameras. It's important to note that when you are profiling a printer you are actually profiling the combination of that particular printer with a particular paper. That profile is unique to a certain paper/printer configuration...a profile created for Rives BFK White paper on a 4 color dye based printer will be totally useless for Arches Cover White on a 7 color pigment based printer.

Furthermore, in addition to providing a lookup table to convert color between devices, a profile can also be used to control a device's color space or color gamut (see glossary).

Also note that, when importing images into Photoshop, it's generally recommended that your RGB images have some color profile (usually Adobe RGB 1998 for digital printmaking) assigned to them.

Links To More Information

• There is an FAQ section on this website which describes working with profiles in The Cave.
• An excellent, more thorough introduction to Color Management is available from Dry Creek Photo's website