I want to desaturate a colour HDRI to B&W to use for the Environment Light. In an older version of Houdini I was able to reduce the saturation of the image in Copernicus and link that to the Environment Light, however can't get his to work properly in Houdini 20.5.

What is the method?

Or if I instead export the converted image from Copernicus, how do I do that exactly? If I have this correct, do I link the output node that makes the correction (HSV Adjust) to a ROP Image Output node in it's COP Path by dragging the node in to this field?

Playing around this is how I set up the export -- is this the way to do it?:

Not sure that helps, but from what i can see it does look like it's working. Your VDB is def desaturated. Only the red self-illum isn't, most likely from your temperature attrib, so it seems like Houdini did the job as expected here. or am i missing somehting?

Cheers,

A.

litote
In an older version of Houdini I was able to reduce the saturation of the image in Copernicus and link that to the Environment Light, however can't get his to work properly in Houdini 20.5.

are you talking about not being able to get op: syntax referencing COP to work for environment light?

tamte

litote
In an older version of Houdini I was able to reduce the saturation of the image in Copernicus and link that to the Environment Light, however can't get his to work properly in Houdini 20.5.

are you talking about not being able to get op: syntax referencing COP to work for environment light?

Hello Tomas, yes that is one uncertainty. I had connected the HSV node to a Null node in Copernicus and dragged the Null node in to the Environment Map field of the Environment Light but it did not seem to work even though syntax appeared. Perhaps I need to manually type in some specific syntax to make the connection? Not sure what this should be.

if you just drag the node to the Environment Map parm it will just paste the path to the node there
that's not a correct syntax, you need to prefix it with op: to reference the actual image that COP node outputs
so if after dragging the path is: change it to:
then it depends on the renderer if it supports that syntax so with Copernicus this will work for Karma, but not Mantra anymore

so if you are rendering with Mantra, use the older COP2 network to desaturate your envmap and then point to that one, COP2 works with Mantra

Thank you so much again Tomas!

I appreciate your explanation. I have tried it and it works.