POV-Ray : Newsgroups : povray.general : Can we eliminate colour banding? : Re: Can we eliminate colour banding? Server Time: 29 Oct 2020 23:21:38 GMT
  Re: Can we eliminate colour banding?  
From: Alain Martel
Date: 18 Aug 2020 17:29:14
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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