Gentoo Archives: gentoo-user

From: Erik <esigra@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] diff command for images
Date: Sun, 27 Jan 2008 15:58:16
Message-Id: 479CAA8E.70305@gmail.com
In Reply to: Re: [gentoo-user] diff command for images by Elias Probst
1 Elias Probst skrev:
2 > Am Sonntag, 27. Januar 2008 14:54:15 schrieb Erik:
3 >
4 >> I need to find the difference between images (like the text-file diff
5 >> command, but for RGBA images). I tried "compare A.png A.png
6 >> difference.png". This should obviously produce some kind of blank image
7 >> because A.png and A.png are the same file, but for some weird reason the
8 >> produced difference.png has recognizable content! Is there a fix for
9 >> that bug or any other image diff program that is sane?
10 >>
11 > The easiest way for doing this, is using GIMP.
12 > - Use one layer for each image
13 > - Use the 'Subtract' mode for displaying the second layer
14 >
15 Not sure how to do this. I am not a graphic artist. But I just open it
16 with "gimp a.png b.png" and press Ctrl-C in one image, switch to the
17 other and press Ctrl-V. That seems to create a second layer. Then I have
18 no idea what to do.
19
20 A simple command would be useful. I might have to regression-test 1000
21 images in a svn commit because some of them seem to have been modified
22 by optipng.
23 --
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