[Openicc] cups-filters

[Michael Sweet]

Till,

Gutenprint offers a 16-bit mode...

On May 16, 2014, at 1:39 PM, Till Kamppeter <till.kamppeter at gmail.com> wrote:

> On 05/15/2014 08:39 PM, James Cloos wrote:
>> 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 have done more investigations on 16-bit Raster files and swapping each
> pair of two bytes in the bitmap (switching endianess) makes the PDF
> coming out correctly. This means something is Little Endian here, either
> Ghostscript's PWG Raster output (I have fixed Ghostscript to use the
> correct cupsRasterOpen so that I get "Ras2" files), or there is an
> Enidan switching somewhere in QPDF (CCing Jay from QPDF).
> 
> As there is no consumer of 16-bit Raster (printer drivers usually take
> 8-bit or 1-bit per color) there was not much testing whether the
> renderers (Poppler, Ghostscript) produce correct 16-bit CUPS/PWG Raster
> output. So it is perhaps possible that the output is Little Endian and
> not Big Endian as it should.
> 
> Note also that I could only test with Ghostscript output, as I did not
> yet succeed to make the Poppler-based pdftoraster produce PWG Raster output.
> 
>   Till
> 
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_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair