[poppler] proposal: render dark text as black

[leidola at newcon.de]

Hi!

> Acrobat (and Reader) do no such thing.  
>
> HOWEVER, depending on your settings we MAY use color management to convert from the source profile/working space to the destination profile of your printing device - such a conversion may lead to better device colors.  This is especially true when working with CMYK-based Postscript devices where we will convert to CMYK as part of the PS generation.

You are right. The difference really comes from using a CMYK color
mode (*). I noticed a difference for that printer when using 

0 0 0 setrgbcolor

instead of 

0 setgray

or 

0 0 0 1 setcmykcolor

in the postscript source. The first one results in halos, the
others not. So using CMYK in any case would be an improvement here.
Also the colors look right when using CMYK instead of RGB. This printer
produces some ugly blue when using 

0 0 1 setrgbcolor

instead of 

1 1 0 0 setcmykcolor.

Is there a easy way to enable CMYK output for poppler? Or maybe this go
to cairo's postscript output.

(*) It produces pure black letters when using grayscale printout mode,
not when using color mode.


Thanks a lot,

O.Leidinger