I am trying to smooth out images of colored wave forms while trying to keep sharp edges.
Example of a source image:
I've had some limited success using surface blur, while the transitions between each color is smoother I am loosing sharpness on edges:
Is there a technique, filter of effect I could employ to get such result ?
here's the result thanks to @boblet
I've found a pseudo-alternative that somewhat achieves the same goal though it's not as pretty.
The thing is to draw gradient lines with the middle color (0.5) being a little darker.
Actually this is the poor man's alternative until I can get hold of the surface blur algorithm which doesn't seem as easy to implement as it sounds.