Hello,

I had a question about converting textures to ACEScg. I have looked at so many forum posts, videos on youtube, etc. They all pretty much have the same instructions and I am still having the same problem.

I have tried converting in a copnet and I tried using PYCO colorspace converter. They both give the exact same results.

Here are my houdini settings. I left linearize non-linear images on. In the vopfilter I used the ocio transform from utility linear srgb to ACEScg.

I did the same thing in pyco (except I left the input on utility texture srgb) and converted to ACEScg. If I imported that image from pyco and compared it to the version in houdini, they are identical. the only issue is that image is darker than it should be. is that normal?

when I say the image is darker, I mean compared to anywhere else. Like in my comparison photo, the texture on the right is how it appears in the default photo viewer, after effects, photoshop, etc. after the conversion to ACEScg, I expected it would look similar. Am I doing something wrong or is this normal behavior?

edit: The reason I want it to match perfectly is because I am trying to use footage I shot and project it as a texture onto geometry. The issue is that now my texture won't match the footage in comp because it is so much darker.

Thanks

No, it won't match because you're viewing with an ACES film curve. The conversion from sRGB to aces doesn't reverse any film curve because the color space is a standard one that doesn't describe any particular tone mapping. The OCIO config you're using has the ACES look enabled on all of the views. This applies a very strong tone mapping effect on the image. More recent configs have views that do not apply the tone map. Usually called "un-tonemapped" or similar. However if you rely on the tonemap for the cg elements to be graded, the plate can have the inverse tone map applied when converting to linear. The ACES 1.X OCIO 1.0 configs usually have a colorspace named "Output - Display - sRGB" that bakes in the tonemap. To reverse it simply convert from this space to ACEScg. On your composite file node, disable 'Linearize Non-Linear Images' and perform the color space conversion afterwards with the vopcop filter.

Another way to convert color spaces is with the command line hoiiotool that ships with Houdini. A simple TOP network can be used to automate the command line tool with a folder of images.

jsmack
No, it won't match because you're viewing with an ACES film curve. The conversion from sRGB to aces doesn't reverse any film curve because the color space is a standard one that doesn't describe any particular tone mapping. The OCIO config you're using has the ACES look enabled on all of the views. This applies a very strong tone mapping effect on the image. More recent configs have views that do not apply the tone map. Usually called "un-tonemapped" or similar. However if you rely on the tonemap for the cg elements to be graded, the plate can have the inverse tone map applied when converting to linear. The ACES 1.X OCIO 1.0 configs usually have a colorspace named "Output - Display - sRGB" that bakes in the tonemap. To reverse it simply convert from this space to ACEScg. On your composite file node, disable 'Linearize Non-Linear Images' and perform the color space conversion afterwards with the vopcop filter.

Another way to convert color spaces is with the command line hoiiotool that ships with Houdini. A simple TOP network can be used to automate the command line tool with a folder of images.

thanks, ill look into this. I have seen the un-tone-mapped with redshift render view and after effects, but it seems to be missing for me

evanrudefx
thanks, ill look into this. I have seen the un-tone-mapped with redshift render view and after effects, but it seems to be missing for me

Yes, you appear to be using the old 1.0 style config which did not have that view. You can add it yourself if you edit the config though.

This app has always worked well for me:

https://mrlixm.github.io/PYCO/standalone/ColorspaceConvert/home/ [mrlixm.github.io]

T

Terence Ziegler
This app has always worked well for me:

https://mrlixm.github.io/PYCO/standalone/ColorspaceConvert/home/ [mrlixm.github.io]

T

Oh yes, I just tried it and it did the trick!