Convert, Edit, and Compose Images
NicolasRobidoux wrote:No matter how much I like it, I'm not sure rose is the very best test image for enlargements because it appears that this thumnail was produced with some sharpening or most likely a ringing scheme (I'd guess (tensor) Lanczos 3 lobes).
NicolasRobidoux wrote:Now for a nice theoretical surprise:
EWA triangle (that is, Clamped Elliptical Weighted Averaging resampling with the bilinear filter kernel) should be a decent scheme in any situation for which downsamling is occuring "all around" (that is, no resizing by making one dimension smaller and the other larger).
And it will be fast.
Actually I think Hermite may be better!
anthony wrote:For upsampling hermite, and triangle is probably good.
ASIDE: A Resized upscale produce the same as there equivelent interpolations as the resize filter becomes 'unscaled'.
For downsampling a Sinc filter works better.
I have not compared Resize Sinc-based filters against Distort Jinc-based filters for downsampling.
Only the upsampling test with the rose which clearly shows the removal of 'jaggies' (block artifacts)
convert image.png -colorspace RGB -resize 50% -colorspace sRGB image_half.png