Single-channel (Red only) .exr files are black on import/export

Basically, the title says it: Whenever I import a grayscale .exr file which only has one channel (Red) - the texture is displayed as 100% black.

I tried using every format possible (BC4u, L8, etc…), but it doesn’t change anything.
Any help is greatly appreciated.

Hi Mr.Kleiner!

Thanks for the bug report - I’ve been able to reproduce it with another Quixel image. It looks like this is a bug in the FreeImage library nvtt_export uses to load EXR files: when the input has only 1 or 2 channels, it tries to load the “Y” channel of the EXR file. However, the single channel in Quixel displacement maps is named “A”; since OpenEXR can’t find a channel named “Y”, it fills the channel with a default value (in this case, black).

I’ll be working on a fix for this (a workaround is to open the .exr file in a hex editor and change byte 0x1C from an “A” to a “Y”, but that’s not a very easy workaround).

Thanks again!

I appreciate such a quick response, thank you!

Hi Mr.Kleiner,

Quick update - we released Texture Tools Exporter version 2023.1.0 today, which now includes a version of FreeImage with this fix! When loading an OpenEXR file with a single channel, it will now load that channel, regardless of its name.



Amazing! Thank you!

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