Color spaces and ICC profiles.

[lprndn]

Hi!

First of all, great work! I'm just starting to use SILE and I feel like it has a lot of potential. I was just wondering if color spaces and ICC profiles were planned to be implemented? I know it's a complicated feature but I find it mandatory for a print focused tool. I'm no dev but I started to look at libtexpdf and justenoughofit and it seems a function is not working (for icc loading?) in libtexpdf... does it make icc profiles impossible?

Thanks,

[simoncozens]

Hi there! It looks like libtexpdf does have the functionality for loading ICC profiles but I haven't looked into any of these functions yet, let alone plugged them into SILE. (And they're not prefixed with libtexpdf_ so won't be exported by the binary.) I think right now they're only used for loading JPEG images. What do you want to do with them?

[lprndn]

Right now, I have nothing precise to do but I know I often need to include ICC profiles for printing. If I'm not mistaking, it's also needed for PDF/X PDF/A conformity. I don't totally understand how profiles affect PDF ( or is it just embedded and that's all?) I might also try to make pdf_setcolor able to deal with with CMYK. It doesn't seem too hard... I'll tell you if I succeed...

[alerque]

Just for cross reference PDF validation is an open issue, see #391.

And by the way of commentary, the colors in the cover of the last book I sent to press came back wildly off and I'm pretty sure the lack of color profiles (and some combination of the print shop's bad sloppy calibration or bad defaults) were to blame. This wasn't SILE's problem since the SILE typography PDF was post-processed and layered into an SVG that was then rendered from Inkscape, but the final didn't have a color profile and it got me in trouble.

I also remember from some LaTeX projects that had raster images that were black and white engravings that I was getting wildly different printing results (overall contrast out of whack) across printers until I started embedding ICC profiles in the PDF and the results across different systems got a lot more consistent.

[shirat74]

Hi,

Is there any progress on this topics? I am the one who implemented the most part of dvipdfmx's (thus libtexpdf) font and graphics support. Maybe I can help you.

[simoncozens]

Hi - I asked this on the TeX-live list but I didn't get any response. I have not done anything with ICC because the code in libtexpdf is commented out and described as "not working". In pdfcolor.h:

/* Not working */
extern int      pdf_colorspace_load_ICCBased      (const char *ident,
                           const char *profile_filename);

I haven't found anyone who knows what isn't working or how to fix it. :/

[shirat74]

Just using ICC profile is easy and libtexpdf already has a capability of doing it. But it does not provide an easy interface for using it. I can't recall it correctly but I think it's actually not "not working" but just "unused".