POV-Ray : Newsgroups : povray.pov4.discussion.general : Suggested v4.0 patch for openexr read where large floats : Re: Suggested v4.0 patch for openexr read where large floats Server Time
3 Dec 2022 20:56:57 EST (-0500)
  Re: Suggested v4.0 patch for openexr read where large floats  
From: William F Pokorny
Date: 24 Jan 2022 06:54:10
Message: <61ee9362$1@news.povray.org>
On 1/23/22 18:57, William F Pokorny wrote:
...
> Found where incoming exr files are at floats and the file has channel 
> values larger than about 2^16 we end up with +inf color channel values 
> internally.
...

I forgot to mention, should you run into one of these exr files with 
values too large for POV-Ray's current exr reader, you can use 
converters to get to an hdr file.

I was able to use: 'iconvert sunflowers_4k.exr sunflowers_4k.hdr'

The openimageio-tools based tooling is able to handle the >2^16 channel 
values and appears to correctly convert to 'workable' hdr files(a)(b).

Bill P.

(a) - An attempt to use incovert from full float encoding to half float 
ran and looks OK external to POV-Ray in that the values are reduced to 
what fits in a half float. However, on attempting to use the half float 
form HDRI, I still had the speckling problem - though the signature of 
the speckles was somewhat different. Not sure what's happening there.

(b) - The hdr format supports less precision and dynamic range than exr 
files, so, it's a non-ideal work around.


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