Some Notes on Color Space Conversions and Rendering Intents

[Erik]

The rendering intents are a method by which the colors in your image are converted from one color space to another, or as I like to describe it: "one brand of crayons to another."

In the U.S. the two biggest crayon manufacturers are probably Crayola and Rose Art. Naturally, they both produce crayons in the basic colors as well as many, many other shades and hues. Imagine two kids each with the same very detailed "color by number" page from a coloring book. One child uses a box of 75 Rose Art crayons, and the other uses the classic Crayola box of 64. When we compare their resulting art, I am sure we'd see that the images look quite different frome each other because only some of the colors match-up well. The Rose Art "crimson red" does not match the Crayola "stop sign red," for example. This example would be akin to the "Absolute" rendering intent where Rose Art "crimson red" is simply substituted for the Crayolas "stop sign red" and vice versa. -This method would not work well for converting files of skin tones and wedding dresses . . .

By invoking the "Perceptual" rendering intent we'll ask our software to consider which red-ish shade of crayons in the Crayola box most closely resembles the Rose Art reds" as the human eye would see it. The problem with this could be that the newly adjusted red may now be very close to a shade of red that is already there, shared between both boxes of crayons and doesn't need to be re-rendered. Having these two shades that were originally not so similar but are now very close wouldn't look right either. So the Perceptual rendering intent will move the other shade too. This way they have a similar visual relationship as before.

Another rendering intent is called Saturation because it moves the "out of range" colors to their closest fully saturated counterpart. It also moves colors within range toward saturation too. This may be very useful if this is what you want . . .

[DRGSin]

Wow...great analogy, made it simple for the dummy to follow along.