[cairo] Quartz filters don't recognize images in PDFs created by cairo

[Serge]

Hi all,

I maintain a program that, among other things, convert colors in PDF 
files using Quartz filters on Mac.

Recently, a customer reported a problem a sent me a PDF file created 
from GIMP using cairo.

After running some tests, I found out that Quartz filters don't seem to 
recognize images in such PDFs.

For example, if there's a Quartz filter that's supposed to convert RGB 
elements to CMYK, it won't change images in this PDF. It will convert 
other elements such as vector objects and fonts.

I never experienced this issue with PDFs created from other popular 
software such as Adobe products, QuarkXPress and Microsoft Office. 
Quartz filters convert images in PDFs from those programs as expected.

Now, I don't think that cairo library does something wrong - my guess is 
that Quartz filters don't support the way cairo stores images in PDF.

On the other hand, evidently, Quartz filters don't have any problems 
with PDFs created from other popular software titles.


So I have two questions:

-Is there a way to make Quartz filters work with images in cairo-created 
PDFs somehow?

-And if not, would cairo developers consider storing images in PDFs in a 
way that let Quartz filters work with them?



Thanks for any info,

Serge