> Date: Wed, 30 Jun 2010 13:59:33 -0400 > From: Stephan Maier <stephan at bwh.harvard.edu>
> I have been verifying the Color Management in XSANE. Great. Do you have a link to a web page with your results? > I found a clear discrepancy between the profiling results > achieved with XSANE and the Argyll (www.*argyllcms*.com) > converting routine cctiff. The Argyll profiling results > agree perfectly with the expected values for my target image. > I was able to reproduce the XSANE results with Argyll's cctiff > by using the same rendering intent, i.e. perceptual, for both input > profile (XSANE: Scanner default color ICM-profile) and output profile > (XSANE: Working color space ICM-profile). ICC profiles typical connect to the Profile Connection Space (PCS). This is eigther Lab or XYZ encoded. During a colour trasnformation your input profile connects to PCS and then goes to output profile, the working or editing space. For a colour trasnformation is only one rendering intent possible. > This leads me to believe the Rendering Intent choice in XSANE setup > applies to both in input and output profile. This approach is not correct, > however. The rendering intent of the input profile, which corrects errors > of the scanner, has to be set to "Absolute colorimetric", since all other > choices perform a white point correction. XSANE lacks the option "Absolute colorimetric" results in a native input whitepoint on the output media. E.g. the colour cast of the device would be projected into D50 or whatever the editing space is and would appear there in. This is useful mostly in pedantic reproduction. Normaly relative colorimetric with black point compensation performs more desirable. > to set this rendering intent independently of the rendering intent > for the output profile (typically the desired output profile intent is > perceptual or relative colorimetric). If there is no thierd profile involved in the colour workflow, there can by definition be no second rendering intent. > Stephan Maier kind regards Kai-Uwe Behrmann -- developing for colour management www.behrmann.name + www.oyranos.org
