Your message dated Sat, 10 Jan 2009 14:55:28 +0100
with message-id <[email protected]>
and subject line Done: -affine option (or its documentation) needs improvement
has caused the Debian Bug report #268269,
regarding -affine option (or its documentation) needs improvement
to be marked as done.
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If this is not the case it is now your responsibility to reopen the
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268269: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=268269
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--- Begin Message ---
Package: imagemagick
Version: 5:6.0.5.2-1
Hi again,
back in version 5.5.7, the documentation for the -affine option was much
more detailed and understandable than it is now. I suggest adding a
complete description of the transform matrix in again, e.g.:
----snip
This option provides a transform matrix {sx,rx,ry,sy,tx,ty} for use by
subsequent -draw or -transform options. The coordinate of a pixel in the
transformed image is calculated as follows:
| sx rx 0 |
(xnew ynew 1) = (x y 1) * | ry sy 0 |
| tx ty 1 |
with the image center as origin for the transformation [this was
incorrectly stated in the 5.5.7 manpage: there it said the reference was
the real image origin (the upper left corner), which was wrong]
The third column of the matrix is always constant... [then came some
more explanations and examples which I do not remember exactly, but as
far as I can tell they were correct and really helpful.]
----snip
Now, there is still one problem: While the transform matrix performs the
rotation ok, the translation is carried out in the wrong direction, e.g.
with positive values for tx and ty, the image does not move towards the
lower right, but towards the upper left. Fixing this in the code would
probably mean breaking the shellscripts of several users out there
(including me :-), so I suggest reflecting this behaviour in the
documentation by showing the real program internal matrix calculation:
| sx rx 0 |
(xnew ynew 1) = (x y 1) * | ry sy 0 |
|-tx -ty 1 |
instead of the equation above.
Greetings & Thanks,
Jan Harnisch
--- End Message ---
--- Begin Message ---
Package: imagemagick
Version: 7:6.3.7.9.dfsg1
>Hi again,
>
>back in version 5.5.7, the documentation for the -affine option was much
>more detailed and understandable than it is now. I suggest adding a
>complete description of the transform matrix in again, e.g.:
Without any answer from your side, close this bug. You could reopen it if you
disagree.
Regards
--
"ROUCARIÈS Bastien"
[email protected]
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--- End Message ---
