[NTG-context] Strange behavior concerning pdf-output of .png-externalfigures

Hans Hagen j.hagen at xs4all.nl
Tue May 21 10:07:01 CEST 2019

On 5/17/2019 10:23 AM, Rudolf Bahr wrote:
> On Thu, May 16, 2019 at 02:40:07PM +0200, Hans Hagen wrote:
>> On 5/16/2019 12:21 PM, Rudolf Bahr wrote:
>>> The problem with artefacts in .png images is still unsolved for me.
>>> I can circumvent it by using .jpg or .tiff images instead of .png images
>>> as long as no transparent areas in the images are needed. As far as I know
>>> .jpg and .tiff formats cannot handle transparancy, do they?
>>> Now in .log files messages like
>>> "luatex warning  > pdfe: invalid 11 0 R object at offset 223611"
>>> can be seen. Please, what do they mean?
>> Does that come from an pdf generated by image magick>? If so, the problem is
>> there ... the last years I've seen lots of converted files with bogus pdf
>> objects. (Kind of harmless but still.)
>> Hans
> No. I never use neither ImageMagick nor GraphicsMagick to generate images in
> .pdf-format. Even with my scanner software I produce always .jpg-images though it
> is capable to produce .pdf-output too. The only .pdf-files I'm doing are made by
> ConTeXt-LMTX!
> I shall append another, interesting MWE. There is a .png-image which is, as it
> occasionally happens, represented as it should, by ConTeXt. And then the same .png-image
> to which I added a red frame by GIMP2.10. This one shows artefacts in ConTeXt!
> I'm adding the .log-file too. There again is a luatex-warning, as I could observe them
> often in ConTeXt-LMTX:
the second image has a mask which is split off (an all 0xFF mask btw) .. 
it shows ok in acrobat so maybe gimp is at fault here?


                                           Hans Hagen | PRAGMA ADE
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