[Bf-cycles] Dithering in preview mode

[Brecht Van Lommel]

Hi,

I think dithering by adding some random noise as Blender does
currently isn't all that useful, and think that error diffusion should
be added once. That's too slow for preview rendering though, and I'm
not sure if dithering is really needed in the preview render.

On Sun, Nov 13, 2011 at 1:31 PM, David <erwin94 at gmx.net> wrote:
> the "Dither" setting is ignored during preview rendering,
> which leads to unattractive banding artifacts in smooth
> surfaces.  In an attempt to improve the situation I came
> up with the following patch, but I am not sure I like the
> solution: it reuses the sobol RNG for dithering, and therefore
> has to pass the rng_state to the tonemap function.

If you think this is important to have, a patch like this could be
committed, but the implementation should be different. Instead of
using the random number generator, a hash function on the pixel x/y
index can be used (hash_int_2d), and this should also only be computed
in case dither != 0.0f to avoid overhead in case dithering is not
used.

Brecht.