POV-Ray : Newsgroups : povray.general : Is it possible to reduce colour banding for JPG output? Server Time: 27 Sep 2020 22:41:25 GMT
  Is it possible to reduce colour banding for JPG output? (Message 1 to 3 of 3)  
From: Kima
Subject: Is it possible to reduce colour banding for JPG output?
Date: 6 Aug 2020 02:45:01
Message: <web.5f2b6da22aa83c09ecc0fada0@news.povray.org>
There are two ways to reduce colour banding in POV-RAY

1. 16-bit depth to have a more accurate spectrum of colours.

2. Dither to fake the colour gradient.

Unfortunately, neither of these methods is available if the output format is
JPG.

If we output a PNG file with +TH, and then, convert it to JPG, the colour
banding disappears.

I wonder why can't we directly save the same effect with JPG output.


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From: Le Forgeron
Subject: Re: Is it possible to reduce colour banding for JPG output?
Date: 6 Aug 2020 09:40:21
Message: <5f2bd005$1@news.povray.org>
Le 06/08/2020 à 04:40, Kima a écrit :
> 
> There are two ways to reduce colour banding in POV-RAY
> 
> 1. 16-bit depth to have a more accurate spectrum of colours.
> 
> 2. Dither to fake the colour gradient.
> 
> Unfortunately, neither of these methods is available if the output format is
> JPG.
> 
> If we output a PNG file with +TH, and then, convert it to JPG, the colour
> banding disappears.
> 
> I wonder why can't we directly save the same effect with JPG output.
> 
> 

You could play with the "Compression" in ini file, to change from the
default 85% quality.

http://wiki.povray.org/content/Reference_Talk:File_Output_Options

Try Compression=100 and see.


About colour bands and other jpeg problem, it is an old story:

https://www.povray.org/documentation/view/3.6.1/169/


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From: Kima
Subject: Re: Is it possible to reduce colour banding for JPG output?
Date: 6 Aug 2020 21:55:02
Message: <web.5f2c7bcfd464a2e9ecc0fada0@news.povray.org>
Le_Forgeron <jgr### [at] freefr> wrote:
> Le 06/08/2020 à 04:40, Kima a écrit :
> >
> > There are two ways to reduce colour banding in POV-RAY
> >
> > 1. 16-bit depth to have a more accurate spectrum of colours.
> >
> > 2. Dither to fake the colour gradient.
> >
> > Unfortunately, neither of these methods is available if the output format is
> > JPG.
> >
> > If we output a PNG file with +TH, and then, convert it to JPG, the colour
> > banding disappears.
> >
> > I wonder why can't we directly save the same effect with JPG output.
> >
> >
>
> You could play with the "Compression" in ini file, to change from the
> default 85% quality.
>
> http://wiki.povray.org/content/Reference_Talk:File_Output_Options
>
> Try Compression=100 and see.
>
>
> About colour bands and other jpeg problem, it is an old story:
>
> https://www.povray.org/documentation/view/3.6.1/169/

Thanks for the link. I had not seen it before and learnt from it.

I actually use Compression=100, and the output is visually identical to PNG
(generally >90). The only problem is that colour banding, which is non-existent
in PNG output with +TH.


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