[Openicc] cups-filters

[Till Kamppeter]

On 05/15/2014 08:39 PM, James Cloos wrote:
>>>>>> "TK" == Till Kamppeter <till.kamppeter at gmail.com> writes:
> 
> TK> How do I proceed with sGray, sRGB, and Adobe RGB?
> 
> Embed an icc profile and use ICCBased (scn, SCN, sh, Bl, Do).
>

What does "(scn, SCN, sh, Bl, Do)" mean?


> (You could use CalRGB for AdobeRGB, using the latter's definition rather
> than an embedded profile.  But it probably is better to use a profile to
> to help ensure that anything reading the pdf recognizes the intent.)
> 
> You can get dfsg-free version of the latter two profiles from:
> 
> https://packages.debian.org/source/wheezy/icc-profiles-free
> http://people.freedesktop.org/~hughsient/releases/
> 

Probably cups-filters will then have to depend on this, so that not each
and every package brings the same profiles into the system. Am I right?

> You may need to create an icc for sGray.  GS has one, but unlike their
> sGray PostScript colorspace definition, their sgray icc is a simple
> gamma 1.8 space.  The sgray profile in graphicsmagick does the same.
> 

How does one create such a profile?

> TK> Also 16 bit color depth with Black and RGB gives broken output.
> 
> Might there be an endian issue?  PDF is big-endian.  The raster file's
> endianness is specified by its 1st 32 bits, 't','S','a','R' for little-
> or 'R','a','S','t' for big-endian.  (The pwg raster spec seems to have
> lost mention of that; the cups raster spec retains that detail.)
> 

I checked Endianess now. my PWG Raster input files are all "Ras2" as
required by the PWG Raster spec (does this implicitly require PWG Raster
to be Big Endian?). These files give broken PDF output: Images are
completely scrambled, look like random pixels or white noise, text and
drawing areas are correct structure but wrong colors.

   Till