For the future -- lcms and big images

[Boudewijn Rempt]

On Tuesday 07 February 2006 16:17, Bart Coppens wrote:
> On Monday 06 February 2006 12:05, Boudewijn Rempt wrote:
> > If we're trying to load a big image that needs converting, either because
> > it doesn't have the display profile or because it's not 8-bit rgb, we
> > convert every pixel, and krita would be much faster if we'd scale first
> > and then apply cmsDoTransform.
>
> There are other reasons as well. Trying the oldfashioned way to debug big
> speed problems (Ctrl+C in gdb when Krita seems 'hang' loading a 3000x3000
> file), I get a lot of times that my Ctrl+C hits a codepath like
> #5  0x00002aaaaf29093a in XPutImage () from /usr/X11R6/lib/libX11.so.6
> #6  0x00002aaaad6b6bba in QPixmap::convertFromImage ()
> from /usr/lib/libqt-mt.so.3
> #7  0x00002aaaad770856 in QPainter::drawImage () from
> /usr/lib/libqt-mt.so.3 #8  0x00002aaab0a4e487 in KisImage::renderToPainter
> (this=0x1123130, x1=0, y1=0, x2=2999, y2=2999,
> and so. Meaning that we'd probably make krita not only faster in the lcms
> path, but also in the Qt path as well. Just so that you know :)

The problem here is, I guess, that we want the OpenGL path to handle scaling 
and conversion to the display profile.

But maybe we can come up with a smart hack to experiment with speeding this 
up?

-- 
Boudewijn Rempt 
http://www.valdyas.org/fading/index.cgi
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