EXR support

[HeCorr]

Motivation
The software doesn't currently support the EXR/OpenEXR image format which is widely used in the VFX and 3D industry.

Description
I would like to see EXR support being added.

Alternatives
The current workaround to using EXR images is to first convert them into PNG images and use those instead, but that's by no means recommended as color values will be clamped.
The same goes to saving images, you need to first save output images as PNGs and then convert them to EXRs, but again, that is not a good idea as PNG cannot carry the amount of information EXR can.

[RunDevelopment]

It shouldn't be hard to add support for EXR images.

Do you happen to have an example file I could use for tests? I can't find any online...

[HeCorr]

Sure thing!

Suzanne.zip

I've included a PNG for reference if needed.

The EXR was saved with these settings:

[RunDevelopment]

This won't be easy after all.

OpenCV does support EXR, but in a really unfortunate way. They are using a somewhat old version of the OpenEXR library under the hood, which has several security vulnerabilities, including ones that enable arbitrary code execution. As such, we cannot enable for support for EXR in OpenCV without compromising security.

opencv/opencv#21326
https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=openexr

[HeCorr]

that's understandable. I believe other software (such as Natron) uses OpenImageIO, but I'm guessing it wouldn't be feasible to implement it into chaiNNer.

[mrjschulte]

Just a small update: with the new "Log to Linear" node you can now bring in a Cineon/logarithmicly encoded 16bit TIFF and use the node to convert that back to Scene linear float.

Please do not forget that currently chaiNNer nodes clamp the float output to 0-1 so there's quite a bit of work to be done to get chaiNNer to support true unbounded floating point workflows.