URL: <https://savannah.gnu.org/bugs/?66114>
Summary: Support embedding bit mapped graphics into a pdf.
Group: GNU roff
Submitter: deri
Submitted: Tue 20 Aug 2024 01:48:30 PM UTC
Category: Driver gropdf
Severity: 1 - Wish
Item Group: None
Status: In Progress
Privacy: Public
Assigned to: deri
Open/Closed: Open
Discussion Lock: Any
Planned Release: None
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Follow-up Comments:
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Date: Tue 20 Aug 2024 01:48:30 PM UTC By: Deri James <deri>
Currently only pdf files can be inserted into a pdf, so the advice was
to use a tool to convert a bit mapped image to a pdf, however, it seems
that the pdf produced may be sub-par. For example, if you load a 16 bit
lossless image with transparency into gimp and save it as a pdf, you end
up with a pdf with a jpeg embedded. So it becomes 8-bit colour, no
transparency, and lossy. It is probably even worse if you load a jpeg
into gimp and save it, since any artifacts in the original file will be
made worse when it is compressed to a jpeg again.
The pdf 1.7 standard allows two image formats, jpeg and jpeg2000 to be
embedded into a pdf natively and requires all viewers to be able to
display the images. So for those two image types it is simply a case of
embedding the file and the pdf viewer has the responsibility of
displaying it correctly.
There is a third method of inserting a graphic into a pdf. Deconstruct
the image into separate colour streams and embed them with flate
compression. This means that any image type recognised by ImageMagick
(used by perlmagick to deconstruct the image) can be used in a pdf.
Implementing this feature would give users much finer control over the
quality of image in the final pdf, and allow 16/32 bit colour depth plus
transparency to be used.
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