[poppler] Testing color management functionality

[Leonard Rosenthol]

On Fri, May 15, 2009 at 9:11 PM, Hal V. Engel <hvengel at astound.net> wrote:

> > Poppler doesn't support overprinting, so #27 and #28 fail.
> > I'm not sure poppler support spot color.
>
> It appears that it does not.
>

Xpdf/Poppler support spot colors by using the alternate value - which is
correct.



> Looking at the PDF specification I see that it is possible for the the
> dictionary for a Device* object to have a default color space specified.  I
> don't know if the altona document has this but looking at the code it is
> clear
> that no attempt is made to get or use the default color space for the
> Device*
> objects.  If it is in the document it should be used any time the Device*
> color space is not a match with the output device color space.
>

Correct, DefaultXXX colors aren't well supported - but should be.   Be aware
that DefaultXXX colorspace can appear at any "rendering level" that has a
resource dictionary, and that the proper "inheritance" of that value
applies...



> Looking at the code it is always using INTENT_RELATIVE_COLORIMETRIC and
> there
> is no attempt to get the Intent from the dictionary in
> GfxICCBasedColorSpace::parse().  So the code is not parsing out the intent
> and
> using that to create the transforms.  I had a look at the code but I was
> not
> able to get the Intent from the dictionary since I am not at all familiar
> with
> the code base.   Perhaps someone who understands how the dictionary stuff
> works could take a look at adding this to GfxICCBasedColorSpace::parse().
>

Intent can come from there places - the 'i' operator in the content stream,
the /Intent key in an ExGState resource dictionary and the /Intent key on an
Image XObject.  You will need to correct handle all of these case to get
intent correct - which may mean having to improve the graphic state stack
since I don't recall if Xpdf/Poppler correctly save/restore the value.

Leonard
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