Re: [Gimp-developer] Slow, artifact-prone redraw when panning in 2.8.0-RC1

... I'm packaging GIMP  for Mac OS X and can confirm this behaviour too. If color management is enabled, redrawing the picture, eg. switching the visibilty of a layer, gets horrible slow.

This is somehow related to first doing color correction and then scaling the image down. 
If I open a photo with e.g. 4800 x 3200 pixels, set zoom to 15%, add a some layer, GIMP redraws the screen very slow. If I set zoom to 100% without changing the size of the image window, redrawing is much faster. 

AFACIS at 100% zoom only the visible part of the image is used for color correction. At 15% zoom, the whole image is visible, and so all pixels are processed although the image is scaled down to fit into the image window.

IMO color management routines should be done on the already zoomed down view. There should be no visible difference to the actual behaviour if you do so, but it will be much faster.


Am 11.04.2012 um 08:43 schrieb Kurt Pruenner:

> On 11.04.2012 01:33, Partha Bagchi wrote:
>> Someone reported for my builds that turning off color management
>> helped. However, for photographs I would not want to turn off color
>> management. They did say they were OK with my 2.7.5 build
> I'm afraid turning off color management didn't make the slightest
> difference...
> I've also just confirmed that I get the same artifacts on my notebook at
> work, so that's 3 64-bit Windows 7 machines with horrible panning
> performance... :(
> By the way - is it somehow possible to install the 32-bit version of
> GIMP 2.8.x on a 64-bit system with the new combined Windows installer?
>> On Tue, Apr 10, 2012 at 7:11 PM, Kurt Pruenner <leak gmx at> wrote:
>>> Hi,
>>> I just downloaded Jernej Simončič's windows build of 2.8.0-RC1 and found
>>> that both on my tablet running Windows 7 with Intel HD3000 graphics as
>>> well as on my desktop, also running Windows 7 but with an ATI Radeon
>>> 5870, panning around an image looks really weird once you pan too fast:
>>> A screenshot doesn't really do it justice, though, so I've also made a
>>> ~30 second screen capture video:
>>> I'm just holding down the middle mouse button and panning the 100%
>>> zoomed image around.
>>> The same thing also happened using one of Partha's recent 2.7.x builds.
>>> Does anyone else get similar results? Panning in 2.6.x was smooth as
>>> butter for me... :/
>>> --
>>> Kurt Bernhard Pruenner --- Haendelstrasse 17 --- 4020 Linz --- Austria
>>> np: Thomas Fehlmann - Next To The Field (Pop Ambient 2007)
>>> _______________________________________________
>>> gimp-developer-list mailing list
>>> gimp-developer-list gnome org
> -- 
> Kurt Bernhard Pruenner --- Haendelstrasse 17 --- 4020 Linz --- Austria
> _______________________________________________
> gimp-developer-list mailing list
> gimp-developer-list gnome org

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