2013/6/30 Guillermo Espertino (Gez) <gespertino@...400...>:
I've been playing with the development version and I noticed that there is some interpolation in downscaling, but it's rather slow and maybe too "smooth" compared to the one in current inkscape stable. Bitmap dowscaling in stable looks sharper and more consistent, downscaling in trunk is too blurry and it seems that it produces different qualities depending on the scaling.
Is that the downscaling patch discussed in this thread? If it is, I'm afraid it's still not acceptable for quality work.
No. The patch is about adding scaling directly into Cairo, using convolution filters recently added to Pixman. These filters are correct from the point of view of signal processing and correctly downscale even pathological images, such as zone plates. The dev version of Inkscape uses its own scaling routine before using Cairo to do the non-scaling part - probably it's not good enough.
The stable version does not actually downscale anything at all - it always samples 4 points per pixel. and uses bicubic interpolation. This means that at high downscaling factors most pixels are ignored.
Regards, Krzysztof