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Bug 66261

Summary:	gdk-pixbuf should dither images in 16bpp
Product:	[Retired] Red Hat Linux	Reporter:	Garrett LeSage <garrett>
Component:	gtk2	Assignee:	Matthias Clasen <mclasen>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	medium	Docs Contact:
Priority:	low
Version:	7.3	Keywords:	FutureFeature
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Enhancement
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2004-05-12 18:10:59 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Garrett LeSage 2002-06-06 20:43:21 UTC

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.0.0) Gecko/20020605

Description of problem:
gdk-pixbuf currently does not dither images in 16bpp; visible banding occurs.

Version-Release number of selected component (if applicable):


How reproducible:
Always

Steps to Reproduce:
1. View images used in GTK+ widgets.
2. Horrible banding occurs on gradients and alpha gradients.

Expected Results:  Images displayed using GTK+2, such as those in Anaconda,
up2date, etc. should look fine in 16bpp, with no banding. Dithering would make
things look "normal".

Additional info:

Comment 1 Owen Taylor 2002-11-01 00:13:20 UTC

It's not at all clear to me that changing 16bpp to dither at 
GTK_DITHER_NORMAL level would be a compatible change... note
also in many cases the problem is that rendering is going
through the alpha-composited path, which can never be dithered.

Comment 2 Owen Taylor 2003-01-14 23:02:27 UTC

Marking various no-need-to-be-private bugs public.

Comment 3 Owen Taylor 2003-01-14 23:03:49 UTC

Marking various no-need-to-be-private bugs public.

Comment 4 Matthias Clasen 2004-05-12 18:10:59 UTC

I think Owen is right. The docs for GdkRgbDither clearly define 
that GDK_RGB_DITHER_NORMAL doesn't dither at 16bpp. This must be fixed 
in the caller by using GDK_RGB_DITHER_MAX. I don't know how anaconda
displays its images...