[XeTeX] Grey fonts with XeTeX

Philip Taylor P.Taylor at Rhul.Ac.Uk
Mon Jun 27 13:15:32 CEST 2016

Hallo Zdeněk --

Zdenek Wagner wrote:
> there is one more important thing. For printing the file should conform to PDF/X which means PDF 1.4. It is important for colour printing, for printing in black higher minor versions of PDF are often acceptable but transparency is not allowed.
OK, I wasn't actually planning to /use/ transparency, I was simply trying to understand how it is accessible from XeTeX -- the documentation says that the fourth byte (fourth hex pair) in the ":color" specified is for transparency :
> color=RRGGBB[TT] 
> Triple pair of hex values to specify thecolour in RGB space, with an optional value for the transparency.
but I have yet to see it have any (useful) effect.
> If you specify colour in the \font primitive as non-transparent black, it might be optimized by the engine to grayscale. If the colour specification contains four bytes, it is RGBA, i.e. it defines transparency which is not allowed. Lookig at your samples it seeme to me that the \font command has higher priority than \color. It seems to me that the preflight is right but there are cases when Adobe Acrobat Professional is not able to fix the PDF properly, in some (but not all) cases ghostscript is more successfull (by ps2pdf14). It is better to solve the problem in the TeX source.
I am very happy to do that !
> If you forget transparency and no one notices it, then it is transparent on the screen, it will be transparent on your office printer but the transparent areas will be printed as black on the offset device. That's why I double-check all included bitmap images.
Fine, thank you.

** Phil.

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