[dvipdfmx] bug with inclusion of a PNG

[Paulo Ney de Souza]

Thanks Shunsaku, I am sorry I have more questions that on the first
e-mail...

On Tue, Jan 12, 2021 at 6:37 AM Shunsaku Hirata <shunsaku.hirata74 at gmail.com>
wrote:

> Sorry there is a correction.
>
> 2021年1月12日(火) 21:10 Shunsaku Hirata <shunsaku.hirata74 at gmail.com>:
> >
> > Hi Paulo,
> >
> > Your PNG images A.png and B.png actually use a calibrated color space
> > as specified in gAMA and cHRM chunks of PNG images. Hence CalRGB
> > should be used.
>

What do you use for checking the ColorSpace of an image?


> > Colors specified in the DeviceRGB color space may look differently on
> > different devices.  Indeed, your color.pdf doesn't show a color
> difference on
> > my smartphone whereas it does on my laptop screen.
>
> This is wrong. I was checking a different file.
>

I think that now it isincorrect. The file "color.pdf" as processed by
xelatex under TL'20
show differences in tonality on laptops and tvs, but not on phones.



> Further inspecting it I found that the calibrated color space used in the
> provided PNG files seems to be using an approximated sRGB space.
> This seems to be causing a subtle difference in the color.
>

Would you mind go into a bit more detail? The differences in color are
completely
gone after one opens and export it in GIMP. How is GIMP able to calculate
the
correct color? THat ought to be part of the original image, no?



>
> > If this is not as you intended, please remove the PNG chunks mentioned
> > above.
>
> I think dvipdfmx output is correct and I suggest doing the above.
>

Would you mind go into a bit more detail here as well? If dvipdfmx is
correct here then
latex,  pdflatex and lualatex are wrong.

Paulo Ney
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