On 3/16/21 1:47 PM, ingo wrote:
> The +Fpg / +Fng switch should result in a 16 bit grey scale image. It only
> renders to 8 bit.
> Adding +Fp16 / Fn16 does nothing as stated in the docs.
> When rendering a gradien I only get 254 colors, instead of the 256 that
> shoud be there for 8-bit.
> 3.8 beta on win10.
The bits per color change in v3.8 made it so the default greyscale depth
is 8. The documentation should indicate this up where Bits_Per_Color=n
gets documented at least.
The documentation does have:
"Previously, specifying a bit-depth for grayscale file output was simply
ignored and the bit-depth was forced to 16 bits per channel. A Change in
version 3.8 now allows for a bit-depth setting."
I'm on Ubuntu working of the v3.8 master commit and the channel depth
options work for me in both color and grey scale(1) with both png and
Could you run a quite experiment? The ppm format supports an ascii
output. Grab a simple scene file. Run:
povray scn.pov +w80 +h80 +fpg8 File_gamma=1.0 Compression=0 +ofpg8
povray scn.pov +w80 +h80 +fpg16 File_gamma=1.0 Compression=0 +ofpg16
Edit both files in a text editor. The difference in encoding should be
(1) - What doesn't appear to be working is the intended and documented
change for ppm (aka pgm) greyscale output. In my testing the output is
still always linear (color output is using bt709). Basically the
following documented change isn't working:
"Previously, the grayscale PPM (technically PGM) output file format
always used linear output. A Change in v3.8 will match that of the
regular non-grayscale PPM format. That is File_Gamma will be honored if
specified, otherwise the ITU-R BT.709 gamma transfer function will be
In fact, I cannot override the greyscale File_Gamma... It should be
working as does the .png grey scale output, but with the bt709 transfer
function, unless the output File_Gamma is set to 1.0 (linear).
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