Adobe Color Space: Not Lovin' It... (Pics)

Started Jun 29, 2004 | Discussions thread
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Iliah Borg Forum Pro • Posts: 21,145
Re: I thought I had a rough idea, but that 2nd sentence...

If you have the patience

if I have English

First, why we need rendering intent. While converting from one color space to another, we deal wit a problem of "nesting" - source colour space can be larger in some (or all) directions then the destination color space. That is, source colour space may have wider gamut then the gamut of destination.

Some colours from the source colour space can get out of the destination space - what to do with those colours? Rendering intent gives the method of dealing with this problem.

4 major rendering intents are called
absolute colorimetric
relative colorimetric
perceptual
saturation

Colorimetric intents leave the colours that fall into destination gamut fairly intact - the colors are only adjusted for accurate reproduction in destination space. Out of gamut colors are compressed to bring them into destination space.

The difference between abs. and rel colorimetric is in how the white is addressed. For relative colorimetric, white from source is translated into white in destination; so, white is preserved.

Absolute colorimetric is designed for proofing, so it makes an opposite - white from destination is considered white in source. Thus I can proof printing on yellow stock paper with my Epson 2100 on white Luster.

With perceptual intent, all the source colours are compressed (even those that actually fall into destination gamut "as is"). This is done to give more space for out of gamut colours. As a result, all colours are "wrong", but the total impression is "right" - as the relations between colours are kept.

Saturation intent maps all the colours individually, without respect to neighboring colours. As a result, different out of gamut colours can be mapped to the same destination colour. This rendering intent is pretty special. I use it with dull images, in order to gain more saturation.

Now, exept for proofing and special cases, I mostly use rel.colorimetric and perceptual intent. In many cases image colours do not occupy the whole gamut of source space. Using perceptual intent in this case compresses the colours unnessessary. Rel. colorimetric intent in this case give more "life" to the image.

To round this up, here is what I do: if the source gamut is much wider then the destination; and number of colours in the image is large enough so that they substantionally fall out of gamut of destination space - perceptual rendering intent is used. Otherwize - relative colorimetric. Preview in convert dialog helps

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