I think I misunderstand what the Lookup TOP does - how come when I connect the default monochromatic Ramp TOP to the 2nd input, and some color noise to the first input, I don’t get monochromatic noise out? Same goes for images.
Hey @mngyuan,
it’s the Index Channel parameter which causes you to see a colored image even though you have a monochromatic image as the Lookup Image. By default this is set to “RGBA Independently” meaning it will use the lookup for each color channel and then combine it again resulting in the same as the input image if using a linear ramp as a lookup.
Some nice examples for the Lookup TOP can be found in the OP Snippets
cheers
Markus
Ah, I saw the split RGBA channels in the viewer in one of the Lookup OP Snippets and realized the TOP I was feeding into the Lookup had pixel format 32bit float RG, so it was coming out yellow even after going through the Lookup. Thanks Markus!