Hi,

I have some dosch hdrs that have a 2.2 gamma (even the lowres ones shipped with houdini are the same).
How can I put a 0.45 gamma correction on them inside Houdini ?
Is there a vop network hidden somewhere I can modify ?

I did the correction in photoshop to test if I had correct results, which I did, but it's not very convenient.

I had a related question, it looks like that there is no way to preview the map orientation right now ? I guess I can create a sphere map the hdr on it and copy the transform over to the env light, also not very convenient

Thanks a lot
Vincent

you could try COPs….

vinz
I had a related question, it looks like that there is no way to preview the map orientation right now ? I guess I can create a sphere map the hdr on it and copy the transform over to the env light, also not very convenient
Thanks a lot
Vincent

If you apply hdri map onto a envlight, and turn on “Render Light Geometry” you will see your hdri in background of the render - which is not “preview” per se, but still it's fast way to see a map in IPR view.

Thanks for the tips!

just out of curiosity, how come your HDR images have gamma on them? Generally HDR images are considered linear to begin with as they are shot raw

you can definitly apply gamma curves in COPs, but if you want to do it directly on the shader, check out the colorCorrection VOP

Why would you gamma correct a HDR ? surely you should be loading up the HDR in cops and setting up a brightness cop so you can step up and down the different F stops you shot and maybe add a clamp cop because Ive always found odd pixels with crazy values. Plus of course then you will want to set your lights up in stops .

Rob

hmm i wonder if SESI will ever add exposure control to their environment light or texture inputs. might be, you know a good idea or something….

In the light intensity value you would put something like pow(2.0,ch(“myexposure”)) but of course then you would also need to strip out the gamma from your textures. There has been some discussion on that here recently as to if its the correct way to go.
Ive done it in the shader before and not had it picked up ever. But I guess its really dependent on your colour pipeline. Personally I prefer lighting in stops !

Rob