NVJpeg2000 Decompressor

[vlazar-ilm]

Hey,

I was experimenting with replacing the openJPH usage for some custom file compression work and the NVidia looked very promising.
I encountered 2 major issues with this:

• Seems NVidia supports only Integer pixels, while openJPH is able to compress floating point as well losslessly through a custom non-linear transform
• NVidia jpeg2k does not support 32bit types (especially float)

Are there any plans to support this ?

[zohebk-nv]

Thank you for reaching out. We havent considered supporting 32 bit float data type.
This is something that we can look into. Would it be possible for you to share details about your use case?

[vlazar-ilm]

OpenEXR just got a new lossless codec, HTJ2K, and I was trying to see what would it take to replace the openJPH implementation with a nvidia jpg2k decompressor (the speed improvements seem quite nice )

Here is the relevant openEXR code: https://github.com/AcademySoftwareFoundation/openexr/blob/main/src/lib/OpenEXRCore/internal_ht.cpp#L330

From my understanding, the data is saved as a standard htj2k stream, with some extra header info.

A short (non-exhaustive) feature set ask:

• Pixel types: UInt32, half, float
• arbitrary number of channels: RGBAZ,. etc
• support for planar buffers ( I suspect this is needed for un-even sampling of channels, eg yuv 422 )

Hope this helps.

[zohebk-nv]

Thank you for sharing the details.

arbitrary number of channels: RGBAZ,. etc

what would be the maximum no of channels that you would require?

[vlazar-ilm]

As arbitrary as it gets :)

Between 1 to a few hundred channels. I don't know what is the maximum number of channels supported by openEXR, but I have routinely seen 150 channel images.

The data comes from a renderer and represents different render passes, eg:
1 channel float32 depth
3 channel half normals
1 channel uint objectIDs

Basically anything that a renderer could output.
The number of components as well as the depths / pixel types need to be unbounded.