A Dilluns, 18 de maig de 2009, Hal V. Engel va escriure: > On Sunday 17 May 2009 12:44:51 pm Albert Astals Cid wrote: > > A Diumenge, 17 de maig de 2009, Hal V. Engel va escriure: > > > Here is a patch that will apply the white point correction after a call > > > to getXYZ(). This patch can be applied to current git. > > > > > > Hal > > > > Do you have a pdf that shows what this fixes? > > > > Albert > > #35 on the altona test pdf shows this for the Lab to XYZ conversion. > Without the white point correction the difference between the upper right > ECI-RGB ICCBased image and the lower left CIELAB image is apparent although > it was not a huge difference. With this fix the difference goes away. > This was testing with color management enabled. This test is NOT valid > with color management disabled. > > I don't have test PDFs for the calRGB or calGray cases. The altona test > PDF does not have any CalRGB or CalGray objects. The CIE to XYZ > conversions do need a white point correction other than CalRGB. At least > that is what is shown in the PDF specification for these conversions. > > After looking closer just now at the CalRGB to XYZ documentation I see that > the CalRGB to XYZ conversion does not use the white point values in the > conversion unlike CalGray to XYZ and Lab to XYZ. But the original code > was doing a white point correction but it was dividing by the white point > so this was clearly incorrect because the conversion should not do a > separate white point correction since this is handled by the matrix. I > made a mistake when I saw the incorrect WP conversion in the CalRGB code > and assumed that it should be the same as the CalGray and Lab code when in > fact it should have been removed. > > Also it might be common for these objects to use the default white point of > X = Y= Z = 1.0 in which case this will not make any difference. But I am > not sure how common this is and the PDF documentation implies that D65 is > the recommended WhitePoint ([ 0.9505 1.0000 1.0890 ]) for CalRGB and > CalGray. > > I have attached a new version of the patch that removes all white point > corrections from the code for CalRGB.
With #35 you mean the circled 35 in altona_visual_1v2a_x3.pdf ? If so pdftoppm generates exactly the same files with your patch and without your patch here, so i guess it's not "fixing" anything for me. Albert > > Hal _______________________________________________ poppler mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/poppler
