POV-Ray : Newsgroups : povray.general : Bits_Per_Color of rendered image-- wrong bit-depth reported : Bits_Per_Color of rendered image-- wrong bit-depth reported Server Time
27 Feb 2024 19:08:21 EST (-0500)
  Bits_Per_Color of rendered image-- wrong bit-depth reported  
From: Kenneth
Date: 25 Sep 2021 17:50:00
Message: <web.614f98a5a3820c14cef624e6e066e29@news.povray.org>
[Windows 10, running v3.8.0 beta 2]

While experimenting with the Bits_Per_Color .ini file feature (I don't know what
the command-line version is for that), and running .png renders,  it seems that
other image-viewer apps are reporting this information wrong. The images
themselves visually show up with the correct specified bit-depth -- although not
in POV-ray's preview window-- but the reported bit-depth does not. I tested this
three ways:
* The typical Windows right-click 'Properties' menu
* I've's Lilysoft/IC app
* Irfanview app

For example, using...
Grayscale_Output=true
Bits_Per_Color=4
....this reports as 8-bits per pixel grayscale.

Bits_Per_Color=12  reports as 16-bit

Another example:
Turning off Grayscale_Output, but setting Bits_Per_Color=4, the apps report this
as 24-bit with 8-bits per color.

From further tests, it seems that POV-ray's .png output image files report
elsewhere as 'only' 8-bit or 16-bit, regardless of the actual bit-depth. This
can get really confusing, when trying to determine later what the actual
bit-depth of a rendered image is!

Perhaps POV-ray is writing incorrect information in its .png output files, in
the file header for example? I haven't yet tested other file-output formats. I
would be curious to know if this happens with rendered images in earlier
versions of POV-ray.


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