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Bug 72863 - Incorrect RGBA resampling in Curve Bend plug-in
Incorrect RGBA resampling in Curve Bend 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 17:13 UTC by Raphaël Quinet
Modified: 2005-01-01 21:56 UTC
See Also:
GNOME target: ---
GNOME version: ---

Attachments
Proposed patch (1.69 KB, patch)
2003-02-06 21:18 UTC, Yeti 		none Details | Review

Description Raphaël Quinet 2002-02-27 17:13:54 UTC 
If two pixels have different opacity values (alpha channel), then their
colors are not averaged correctly by the Distorts->Curve Bend plug-in (only
if the "smoothing" option is checked).
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 2003-02-06 21:18:38 UTC 
Created attachment 14173 [details] [review]
Proposed patch
Comment 2 Yeti 2003-02-06 21:27:06 UTC 
Attached patch against CVS HEAD.

It fixes it, but don't ask me how. The plugin code is ugly and should
go to stamping mill or at least pass through indent.
Comment 3 Sven Neumann 2003-02-18 17:53:40 UTC 
2003-02-18  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:

	* libgimpcolor/gimpbilinear.c (gimp_bilinear_rgba): fixes RGBA
	resampling in Map Object and Lighting Effects plug-ins (#72876 and
	#105496).

	* plug-ins/common/curve_bend.c: fixes bug #72863.
	* plug-ins/common/deinterlace.c: fixes bug #72856.
	* plug-ins/common/gauss_iir.c: fixes bug #72848.
	* plug-ins/common/gauss_rle.c: fixes bug #72849.
	* plug-ins/common/iwarp.c: fixes bug #72865 (except preview, see
	comment).
	* plug-ins/common/mblur.c: fixes bug #72850.
	* plug-ins/common/pixelize.c: fixes bug #72851.
	* plug-ins/common/polar.c: fixes bug #72866.
	* plug-ins/common/ripple.c: fixes bug #72868.