POV-Ray : Newsgroups : povray.general : 16 bit gray scale : Re: 16 bit gray scale Server Time
25 Sep 2021 11:46:28 EDT (-0400)
  Re: 16 bit gray scale  
From: William F Pokorny
Date: 28 Mar 2021 10:41:28
Message: <60609598$1@news.povray.org>
On 3/17/21 8:51 AM, William F Pokorny wrote:
> On 3/16/21 1:47 PM, ingo wrote:
> --- Bug

Summary. Three issues found as a side effect of checking the v3.8 bit 
depth feature.

A link to a more detailed thread given the web forums/news interface is 


1) In v3.8. Greyscale ppm/pgm output not respecting the File_Gamma 
setting. Not a feature of v3.7.

2) In v3.8. The png sRGB chunk is not output unless the File_Gamma is 
set to srgb though the default output uses srgb. Default png write and 
immediate read won't match exactly. Release v3.7 looks OK to quick tests.

3) In v3.7 and v3.8. Incorrect greyscale png file input where bit 
storage depth <= 8 and input is non-linear (gamma!=1). In v3.8 this the 
default png greyscale write and read.

Aside: On the web view I currently see a mistaken, partial 
povray.beta-test news post with the suffix part 1, which I immediately 
deleted from Thunderbird. Please ignore it for the more recent and 
complete thread.

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