Quadratic (quadratic B-spline smoothing) works well with EWA

[NicolasRobidoux]

Preliminary testing suggests that the Quadratic filter (2nd degree B-spline with support [-1.5,1.5]) works well with EWA (when upsampling; downsampling, of course, is always another story):

Code: Select all

convert rose: -define filter:filter=Quadratic -distort Resize 3000% rose_quadratic.png

Of course, it's blurry and halo free.

[anthony]

It is also essentially a fit of the Gaussian filter That explains why it has low aliasing effects, at the cost of blurry effects.

[NicolasRobidoux]

... or pushing the luma and chroma channels through EWA with BC-splines with different c: closer to Cubic for the chroma than for the luma, esp. when using chroma subsampling.