Conversion between color spaces is complicated because there are different compromises to be made according to the effect desired. Also, viewing conditions can completely alter the appearance of color, and this must also be taken into account. The rendering intent specifies the intention and helps choose what compromises must be made.

The ICC profiles define four standard "rendering intents" as follows:

Click to expand/collapse hidden textPerceptual rendering

Colors are represented in a manner that provides a pleasing perceptual appearance.
This means that most colors are altered in order to preserve color relationships.

Click to expand/collapse hidden textRelative colorimetric

This maps the colors such that the original white-point maps to the new white-point. For example, a full RGB "white" is reproduced as un-inked paper. Colors that are "in gamut" are reproduced exactly. Out of gamut colors cannot be reproduced as accurately.

Click to expand/collapse hidden textAbsolute colorimetric

Colors are represented solely with respect to the light source so that they be measurably the same in the new context. This does mean that they may not look the same.
One effect of this is to represent the true color of the white on the transformed medium.
For example, as displays have a bluer "white" than printer paper, this may render an RGB white as a bluish tint when printed.

Click to expand/collapse hidden textSaturation

Colors are represented in a manner that preserves or emphasizes saturation.
A typical use might be for business graphics, where it may be more important to distinguish dark shades from lighter hues, rather than the actual color.

Note that some color profiles express some rendering intents better than others.