Which Should You Use?
I'm often asked the question "which rendering intent should I use?" The only sensible answer is that you should use the rendering intent that produces the result you like best. But for most seekers of knowledge, that's not a very helpful answer.

Conventional wisdom has it that one should use perceptual rendering for natural imagery such as scanned photographs or digital camera captures, and relative colorimetric rendering for vector art such as Illustrator or FreeHand files. As a basic rule of thumb, this isn't a terrible approach, but it doesn't always yield the best results.

Figure 6a: Original image.

Figure 6b: Converted for a Web press space using perceptual rendering.

Figure 6c: Converted for a Web press space using relative colorimetric rendering. Note the plugged-up detail on the top of the cone of red yarn.

Many photographic images could benefit from a relative colorimetric rendering, rather than a perceptual rendering. Remember, color-management systems know nothing about the content of the image itself; they only know about the gamut of the color space the image inhabits. When you use perceptual rendering, the color management system applies the same gamut compression to all images, even when the image contains no visually or aesthetically significant out-of-gamut colors. For instance, with pastel images, perceptual rendering will apply unnecessary gamut compression, while relative colorimetric rendering may produce a result that's more faithful to the original.