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Le 2020-08-18 à 11:51, Kima a écrit :
>
>
> I am struggling to find a way to visually eliminate colour banding. As I
> understand, there are two methods, but both just reduce banding, and they are
> still clearly visible.
>
> Consider a simple scene of
>
> camera {location <0,30,-12> look_at <0,0,0> angle 45 right 16/9*x up y}
> light_source{<-5,5,-3> color rgb<1,1,1>*0.7 }
> plane{<0,1,0>,0 pigment{color rgb<1,1,1>} }
>
> 1. bit-depth. Theoretically, the 16-bit colour should provide enough range to
> eliminate colour banding. However, in my experience, this just makes the bands
> smaller.
>
> Command: povray +Iin.pov +MB +A -D +V +W4000 +H3000 Bits_Per_Color=16 +Oout.png
> Output: https://ibb.co/BP72rbS
>
>
> 2. Dithering. Merges the band edges but, they are still visible. I tried some of
> the Dithering methods, but not much difference.
>
> Command: Command: povray +Iin.pov +MB +A -D +V +W4000 +H3000 +TH +Oout.png
> Output: https://ibb.co/bscqT65
That image don't show any colour banding on my display. Just a smooth
gradient.
>
> Using both methods did not improve any further. +TH has no visible effect on
> 16-bit output.
>
> Do I miss something?
>
>
>
Simple. It is impossible to totally eliminate colour banding when using
any numeric representation of the image. 8 bit per channel is the best
that you can get. Your video card just can't do better than that.
The only way to actually eliminate it would be to use an analogue
signal, and it's just not possible to have that with current technology.
Also, even if you save your image in a 64 bit per channel format, when
displaying the image on your monitor, it get reduced to 8 bit per
channel due to the limitation of the video hardware, both the video card
and the monitor, as well as your video drivers. It can get even worst
than that, low end/entry level/cheap displays could be limited to 6, or
even 5 or 4, bit per channel. Bad, or badly configured, video drivers
can also cause this.
The image that you see on your monitor can have much worst banding than
your image effectively have.
Alain
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