When rendering in 2.5 I get banding in the sky with blending turned on. It’s much worse than it ever appeared in 2.49.
I have turned the ‘dithering’ setting all the way up to 2, yet still the banding persists.
You can see the comparison between 2.5 and 2.49 in the renders I have attached (sorry they are just basic cube renders, I’m just trying to point out the banding issue).
Does anyone else suffer from this problem with 2.5? I’m using revision 25095 from Graphicall for PPC macs running Tiger.
Thanks
Edit: The 2.5 render is on the left and the 2.49 on the right. You need to click to enlarge them to see the banding issue.
Yeah, I get that too. It may be related to the final output image type. Have you tried outputting to Open EXR? Also try turning on Color Management in 2.5.
Is the blend mode set right for the background (world)? The banding comes from having to little contrast between shades (aliasing/banding), perhaps you need Paper blend type?
No, the banding is there because the dither setting was ignored. It’s a bug.
Dithering introduces pixel noise to distribute quantization errors that occur when color resolution is reduced from e.g. 16bit to 8bit. Load the picture into a paint program and flood-fill a random spot in the background with red or green. You’ll see that there is no pixel noise at all. Dithering was not applied.
Just a quick hint, what also helps sometimes with quantization, at least with video compression, is to introduce a small amount of color into gradients by slightly mixing in a 4-corner gradient with different colors in each corner, just enough to cause minute variations in values.
I tried rendering again with more contrast between the two sky background colours, whilst also setting it to paper, and found that it did help to reduce the banding, although it is still slightly visible.
I think the problem must be that the default colours for the background don’t have enough contrast between them. That, and also dithering not working yet. Would that simply be because it hasn’t been coded yet, or is it more likely to be a bug that needs reporting?
It seems like a pretty obvious thing, so I doubt it needs reporting.
Edit: I’ve just discovered that dithering does actually work when you have color management turned off. The opposite to what you suggested, Atom. Not that this helps much, as I want to be working with color management turned on.
