Some examples of how eog displays colours compared to imagemagick's display.
These files were generated as follows, using ffmpeg:
ffmpeg -filter_complex color=black:256x256,geq=X:240:128 -hide_banner -frames
1 geq.png
ffmpeg -filter_complex color=black:256x256,geq=X:240:128 -hide_banner -frames
1 geq.jpg
ffmpeg -filter_complex color=black:256x256,geq=X:200:128 -hide_banner -frames
1 geq-200.png
ffmpeg -filter_complex color=black:256x256,geq=X:200:128 -hide_banner -frames
1 geq-200.jpg
ffmpeg -filter_complex color=black:256x256,geq=X:128:128 -hide_banner -frames
1 geq-128.png
convert geq-200.png -quality 100 geq-200.png.jpg
convert geq-200.png geq-200-convert.png
So these are images with a y (or is it y'?) value that ranges from 0 to 255,
while the u value is at the mpeg range maximum for u of 240. The jpg and png
images are different because the jpg images clip the y range when expanding it
from 16~235 to 0~255, while the png images when converted to rgb allow the y
values outside the normal range to affect the output colour. So the jpg output
from convert is visually identical to the png it comes from, but on the edges u
and v both have a gradient to produce those colours.
Then I took a screenshot of how eog displays geq-200.png, as well as a
screenshot of how imagemagick (display) displays png, and combined them
in GIMP. The jpgs are displayed roughly the same in both programs, other
than the differences due to clipping when expanding to jpeg range.
Firefox displays the images output from ffmpeg the same way as imagemagick, but
displays the png output from imagemagick's convert almost the same as eog does.
This similarity is much higher than for the images I tested for the original
bug report. I took a screenshot of Firefox's display of geq-200-convert.png,
cropped it and placed it on top of a screenshot of eog's output of geq-200.png
(which is displayed exactly the same as geq-200-convert.png by eog), used the
difference filter and flattened the image. ("flattening an image" might be used
incorrectly here, but it's what the option is called.)
Then I used the threshold operation, from 1 to 255, so the vertical
lines are where they differed. All but one of the lines disappear at
threshold 2, the last disappears at threshold 5.
** Attachment added: "geq.png"
https://bugs.launchpad.net/ubuntu/+source/eog/+bug/1436595/+attachment/4366249/+files/geq.png
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https://bugs.launchpad.net/bugs/1436595
Title:
Images too bright
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