[poppler] rotated/downsampled images

Thomas Freitag Thomas.Freitag at kabelmail.de
Sat Jul 28 00:33:38 PDT 2012

Hi Arpit & Bill!

In a quite short period You both offer to implement a better algorithm 
for rotated / scaled images than the Bresenham algorithm, one of You 
wants to implement the bilinear, the other the bicubic interpolation. 
Would be funny to see, which one is the better compromise between speed 
and quality.
In splash always the scaling of an image is done first with 
Splash::scaleImage, and then the scaled image will be rotated in i.e. 
Splash::arbitraryTransformImage. So this is the place where You can 
implement a new algorithm.
I know, that we get sometimes a poor quality for slightly rotated 
images, see i.e the wheels in 
http://www.it.piaggio.com/media/mp3hybdepita.pdf on the first page, and 
therfore it would be nice to have a better algorithm. But we must keep 
the speed in mind, because poppler is often used to display a PDF in 
time under unix. If You need any assistance, i.e. proof Your new 
implemented code with a lot of PDF, I'm willing to support You.


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