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

Alastair M. Robinson wrote:

The problem concerns very dark, saturated colours becoming excessively
light when transformed to a profile with poor black density.


http://i14.photobucket.com/albums/a346/robinsonb5/IT8_sRGB.jpg
http://i14.photobucket.com/albums/a346/robinsonb5/IT8_Glossy_Proof.jpg
http://i14.photobucket.com/albums/a346/robinsonb5/IT8_Tesco_Proof.jpg
http://i14.photobucket.com/albums/a346/robinsonb5/IT8_Plain_Proof.jpg


Hmm. It's hard to say much about these images, without anything to
compare them to. The last one for instance, might be quite reasonable,
if the plain paper has a poor black point (was this running RGB to
the printer, or CMYK ? If the latter, it would be worth double checking
the ink limits used for the test chart, and during profile creation.)

I would need the .ti3 & compile command line for (say) the plain paper to
make any judgement as to whether things are working as expected here.

The general behaviour of the grey wedge is consistent with an absolute mapping,
in that it (plain paper) tracks the original down to wedge 12, and then
flattens out (clips).

The Proofing Prism result is completely inconsistent with T8_Tesco_Proof.jpg.
By the latter, the black point on plain paper has an L of 22-23, but by the
former, it is 4! Which is correct - can you measure the black L value
independently to determine this ?

Graeme Gill.


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