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Bug 72871 - Incorrect RGBA resampling in Whirl and Pinch plug-in
Incorrect RGBA resampling in Whirl and Pinch plug-in
Status: RESOLVED FIXED
Product: GIMP
Classification: Other
Component: Plugins
1.x
Other All
: Normal normal
: ---
Assigned To: GIMP Bugs
Daniel Egger
Depends on:
Blocks: 70335
 
 
Reported: 2002-02-27 17:26 UTC by Raphaël Quinet
Modified: 2005-01-01 21:56 UTC
See Also:
GNOME target: ---
GNOME version: ---

Attachments
Proposed patch (3.96 KB, patch)
2003-03-02 01:58 UTC, Yeti 		none Details | Review

Description Raphaël Quinet 2002-02-27 17:26:07 UTC 
If two pixels have different opacity values (alpha channel), then their
colors are not averaged correctly by the Distorts->Whirl and Pinch plug-in.
It looks like the RGB channels are resampled without taking the opacity
into account.  As a result, the (invisible) color of a transparent pixel
can bleed into an opaque pixel.  The resulting image is incorrect.

See bug #70335 for some test images and a longer description of the
problem.  This problem affects many other tools and plug-ins.
Comment 1 Yeti 2003-03-02 01:58:14 UTC 
Created attachment 14718 [details] [review]
Proposed patch
Comment 2 Yeti 2003-03-02 01:59:16 UTC 
Attached a patch against 1.3.12.

Again, locally defines gimp_bilinear_pixels_8 ().
Comment 3 Sven Neumann 2003-03-02 12:35:03 UTC 
If you send me a patch for libgimp/gimpbilinear.[ch] that adds the
proposed function with inline docs suitable for gtk-doc, I'll apply it
so that you can base your patches on the extended functionality of
libgimpcolor.
Comment 4 Sven Neumann 2003-03-16 17:58:10 UTC 
Yeti, I'd appreciate if would send me a combined patch for the
plug-ins you fixed lately. As you probably know,
gimp_bilinear_pixels_8() has been added to libgimpcolor in the meantime.
Comment 5 Sven Neumann 2003-03-17 11:21:10 UTC 
2003-03-17  Sven Neumann  <sven@gimp.org>

	Applied patches from David Necas <yeti@physics.muni.cz> that fix
	incorrect RGBA resampling in a number of plug-ins:

	* plug-ins/common/fractaltrace.c: fixes bug #72873.
	* plug-ins/common/tiler.c: fixes bug #72875.
	* plug-ins/common/waves.c: fixes bug #72870.
	* plug-ins/common/whirlpinch.c: fixes bug #72871.