can i put a hard limit on channel values?

[hello and thank you]

situation: the exr pass from c4d that i am using in fusion has pixel rgb values that go wayyy beyond white. like, R 3.232123 G 2.94234 B 3.14192 or something.

what i'd like to do: limit each of those channels to 0.95, or even just 1.0

is that possible? perhaps with an expression? maybe this has to be done in the c4d rendering?
but it would be soooo useful making masks from my various passes, subtracting one pass from another, etc.

thanks

You can easily clip values to 0..1 by adding a Brightness/Contrast node after the Loader/MediaIn, and ticking "Clip White" and/or "Clip Black". That will cut off higher/lower values, eg values of 2, 35 and 50 would all be changed to 1.0 and -15, -50 and -200 would all be 0.0.

If you want to normalise the values instead, like if the value range is -50.0 .. 35.0 and you want to remap it so that 35 becomes 1.0 and -50 becomes 0.0, and every value in-between is adjusted proportionally, you can do that with the CopyAux node, set up something like this:


As you can see there's a Detect Range button to try and find the correct values for Min/Max. However when I tested it it didn't seem good at detecting both negative and positive ranges at once, eg when the lowest value was -45 and the highest 50 it gave 0..50 so I had to enter -45 manually as the min.

thank you tom.
so often there's a simple answer in a node i just never use. [because it had seemed that color correct node covered brightness/contrast just fine]
the normalization info will come in handy too, i'm sure.
much appreciation.