In article <dbroeo$pr6$>,
"Steven Jones" wrote:
What is colour management? When I create a new document in photoshop, it offers me a choice of colour management profiles. I’m new to Photoshop, having switched over from Paint Shop Pro.
The idea behind color management is very simple; the execution is quite complex.
Here’s the simple overview: In a computer graphic, a color is indicated by a series of numbers. These numbers may indicate RGB values, or CMYK values, or Lab values, or whatever. So, let’s say you have the RGB values 165, 49, 79. What color is that? If you type those numbers in Photoshop’s color picker, you’ll see that it’s a shade of red.
But here’s the pickle. Exactly what shade of red? If I look at that shade of red on the LCD on my computer laptop, and you look at that shade of red on a cheap Viewsonic monitor, and someone else looks at that shade of red on an expensive Barco monitor, we will see three DIFFERENT colors. Different computer monitors display the same color slightly differently. Who is right? What is the "real" color of 165, 49, 79?
That’s what color management is all about. The theory behind color management is this: First, you establish some set, fixed idea of what 165, 49, 79 looks like. This is your working space. There are different standards; for example, if you use the Adobe RGB standard, it says "165, 49, 79 looks exactly like THIS, and anything that does not show it this way is wrong," but if you use the sRGB standard, it says "165, 49, 79 looks like THAT, and anything that doesn’t show it that way is wrong."
So you choose a working space, say Adobe RGB. Now you know what 165, 49, 79 is SUPPOSED to look like–you have a reference standard that is the same everywhere. Everyone working in Adobe RGB knows exactly what 165, 49, 79 is supposed to look like.
The second part of the equation has to do with your monitor. Someone somewhere says "Ahh, yes, Viewsonic monitors–they are too dark and too blue. 165, 49, 79 is supposed to look like THIS, but instead it looks like THAT." This is a "monitor profile."
In Photoshop, you choose a working color space and a monitor profile. The working color space tells Photoshop "This is what 165, 49, 79 is supposed to look like." The monitor profile tells Photoshop "You are using a Viewsonic monitor. It makes things too dark and too blue. Here is how you must change 165, 49, 79 so that it looks like what it is supposed to look like on the screen."
Now, there’s more to it than that, of course; this discussion is extremely simplified. (For example, I haven’t discussed output to a printing device at all.) But it’s the basic idea. Color management is a way of changing the colors of an image on your screen so that if a whole bunch of people open the image on a whole bunch of different computers with a whole bunch of different monitors, it looks (as far as is possible) the same on all of them. Without color management, an image looks different on every kind of computer you open it on, and on every kind of printer you print it on, and there is not a set "reference" that says what the image is really "supposed" to look like.
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