Multimattes and bit depth

[francomanko]

Hi, is there a way of rendering multimattes at 8 bit, when the main renders are 16bit?

[^Lele^]

No, but you can post-convert them to another format.
Or you can save split channels to an 8bpc format.
EXR doesn't support 8bit channels.

[francomanko]

Hi, thanks for reply, yeah, would be a good option maybe? I wasnt using exr, but 16bit png...just didnt need the multimattes hoggin up my harddrive being 16bit as well.

[^Lele^]

Hi, thanks for reply, yeah, would be a good option maybe? I wasnt using exr, but 16bit png...just didnt need the multimattes hoggin up my harddrive being 16bit as well.

PNG are 16 bit but Integer.
You are losing most, if not all, the benefits of 16bpc as floating point.
You'd find EXRs compact quite efficiently, and a MM RE is generally very, very well compactable, thanks to the usually large monochromatic areas, and lack of noise.
If you switched to multi-layer EXR (via the raw file saver), you'd likely find yourself saving some space already, i'd wager, on that old PNG tech.
Feel free to try it out and let me know if it works better, or not, for your specific case.

[francomanko]

ok will do thx

[Buck]

I'll 2nd Lele here, solid matte passes in EXRs generally don't add much file size.