[reportlab-users] Patch for inclusion of CMYK images as CMYK, not converted to RGB

[Robin Becker]

Stevens, Ian wrote:

> The following patch to pdfimage includes unconverted CMYK images in the

> PDF to preserve colours. We have clients who pass their PDFs through a

> preflight tool before sending it to press and want all content to be

> CMYK. The patch uses PIL's Image.mode to decide whether to convert the

> image. We've been using this on our production servers since 2.1 without

> problem.

>  

> Would it be possible to include this in the upcoming release? 

>


Yes, I see no obvious problem here. I think it's more sensible to move the bpp 
setting into the first part of the patch though.

We should probably think more about greyscale and other common image formats, 
but not today.

As for CMYK in general we have had patches in the past related to CMYK in jpegs. 
I notice in the code where we load a CMYK image from jpeg that we set a decode 
array parameter which seems to reverse the sense of the colour values so instead 
of running 0-1 they run 1-0 instead. Anyone clever here know why we have to do 
that. I seem to remember when we started doing these patches that the tool (name 
forgotten) which was creating the CMYK images required this transform (otherwise 
all the colours were messed up).


> Thanks,

> Ian.


--
Robin Becker