[argyllcms] Re: Absolute colorimetric - dark saturated colours excessively light

Hi,

Gerhard Fuernkranz wrote:

my understanding is, that Argyll clips to the nearest color on the gamut hull. Are you absolutely sure that DeviceBlack is really closer? Have you verified this computationally?

No, not yet. I have, however, verified that closer (subjective) visual matches are possible. We needed to produce some paint charts at work, so I sampled XYZ values of the swatches with the colourmouse, and transformed to the printer profile using Absolute Colorimetric. Dark saturated colours came out too light.

I tried knocking up a program to do the interpolation using the RSPL engine and the RGB / XYZ data in the printer profile's TI3 file directly.

The results were noticeably better - still room for improvement, though - I could probably get closer still if I put in the time to figure out how to use clipping vectors.

If you look at profiles generated by other profiles
(e.g. ProfileMaker), you'll see that they behave similar as Argyll for colorimetic intent. However, the ICC spec leaves open, _how_ out-of-gamut colors should be clipped, so this is implementation dependent. For a pleasing reproduction with gamut compression, actually perceptual intent is intended.

Thanks. I'll dig out a vendor profile for the printer and see how that compares.

I do understand the difference between the colorimetric and perceptual intents, and have to say that I'm very pleased with the photographic results I'm getting using Argyll's perceptual mapping.

As I say, I'm just a bit surprised at which colours are being chosen to replace the out-of-gamut colours, especially for the plain paper example; I'm pretty certain there are darker, more suitable shades available.

All the best,
--
Alastair M. Robinson

Other related posts: