And I’m not talking about the render at twice the size and scale it down thing.
Say you rendered a .jpg, uh oh, a bunch of tiny little artifacts and some banding, what do you do?
In my newest clouds image I was faced with the problem of small .jpg artifacts when looking close and some banding, so this is what I did in the compositor
1). Bring in the image
2). Scale it up to 4500x4500 pixels
3). Gaussian blurred it with the values at 12
4). Scaled it back down
5). Took the scaled up image, drew it through another compositor branch an edge filter and a colorband and joined that with the former by plugging it into the size input for the blur.
I found from some testing that it made the banding look a little better and wiped out the tiny artifacts while giving very little loss of sharpness. The effect was most noticable under high contrasts and after I tested edge enhancing in a paint program, in the initial image, the edges shown were blocks, after the compositing was done, it was a fine grain.
From 100% scale it looks almost identical, but zoom in closely and you’ll need a sort of very fine grain where little artifacts used to be in areas with little contrast. The advantage of this is that rendering it at twice the size is not needed, you can render it at the origional size then use the trick to do what I described above.
EDIT: Found my trick also reduced sharpness on most images, no worries, I simply added another step to keep as much sharpness as possible while getting rid of artifacts.
So you found any tricks to improve quality without rendering at twice the size?