ImageMagick only reads 32b EXR alpha as 16 bit?

Post any defects you find in the released or beta versions of the ImageMagick software here. Include the ImageMagick version, OS, and any command-line required to reproduce the problem. Got a patch for a bug? Post it here.
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wesw
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ImageMagick only reads 32b EXR alpha as 16 bit?

Post by wesw » 2019-02-15T13:52:41-07:00

I have a heightfield rendered from Houdini, stored as 32 bit floats in range -1 to 1, saved as a single channel EXR. Other applications read this exr file as 32-bit single channel.

Using the command line tools, I cannot get IM to read the Alpha channel as anything but 16 bit. Even with -depth 32, it will identify in verbose as "Depth: 32/16" with Alpha listed as 16-bit and Red/Green/Blue as 1-bit. I have also tried -define exr:color-type=A, also G, R, Y to no effect.

Version: ImageMagick 7.0.8-25 Q16 [HDRI] x64 2019-01-28 (dll)

I can perform crop on the image with exr:color-type=A, but the result being 16bit quantizes the heightfield. I have also tried -define quantum:format=floating-point with no luck, seems irrelevant if IM reads the original source image channel as 16bit.

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fmw42
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Re: ImageMagick only reads 32b EXR alpha as 16 bit?

Post by fmw42 » 2019-02-15T14:26:33-07:00

I believe that Imagemagick only handles currently 16-bit EXR files. I am not sure if it handles transparency or not.

wesw
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Re: ImageMagick only reads 32b EXR alpha as 16 bit?

Post by wesw » 2019-02-19T11:57:28-07:00

I may have misread the documentation says the HDRI version should read/write 32b and negative values. I could be wrong, my tests seem to identify RGB as 32b but never A, leads me to believe that RGB may support 32b whereas alpha was neglected. :(

If there is no support for 32 bit single-channel, is a fix on the horizon any time soon?

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