[Just realised that the XeTeX list should have been cc'd, so doing so
now and will forward Paulo's original images as attachments]
Philip Taylor wrote:
Ulrike Fischer wrote:
I can't reproduce your problem with the files you provided.
How do you compile? Which TeX-System do you have? And which viewer
do you use to view the pdf? Can you provide the pdf you get?
For me (Windows 7 64-bit Enterprise, TeX Live 2020), PdfLaTeX does
/not/ shew the problem whilst XeLaTeX does. The artifacts are more
visible in the TeXworks previewer than in Adobe Acrobat CC, but are
nonetheless visible in the latter.
/Philip Taylor/
/--------/
I have (a couple) of PNG images with a background color of, for
example, RGB(80,64,83), that when placed on a page of the same
background color with {graphicx} -- they show a distinct tonality
against the background -- which is of the same color.
````
\documentclass{report}
\usepackage{xcolor}
\definecolor{bgcolor}{RGB}{80,64,83}
\usepackage{graphicx}
\pagestyle{empty}
\begin{document}
\pagecolor{bgcolor}
\includegraphics[width=0.5\textwidth]{A.png}
\quad
\includegraphics[width=0.5\textwidth]{B.png}
\medskip
\includegraphics[width=0.5\textwidth]{A-gimp.png}
\quad
\includegraphics[width=0.5\textwidth]{B-gimp.png}
\end{document}
````
Checking the colors in the included files one can see they have
changed from (80,64,83) to (71,56,74) in the included images.
Just opening the images on `GIMP` and exporting it as-is with the
default choices of
export-settings.png
fixes everything and the new inclusion now gets the exact color they
were set to begin with, the same as the background, as shown below
(second line).
together.png
What is that TeX needs from the PNG's to preserve their color when
included in a page?
Paulo Ney
PS. For experimentation here are the same images, before and after
opening with GIMP.
B-gimp.png
A-gimp.png
B.png
A.png
