saturation model from photoshop or nuke

[sagrothWXF5L]

I used a lot of alRemapColor to desaturate things, but now I want to replace them with ai (a lot of them, so, with a script, without eyeballing the visual result). Desaturation with alRemapColor produces the same result as Nuke and Photoshop, but aiColorCorrect (as well as maya's remapHSV and colorCorrect) makes a very different result.

Is there a way to replicate the same desaturation effect as in Nuke/Photoshop with ai nodes?

[sagrothWXF5L · Accepted solution]

Ok, apparently alRemapColor uses Luminance mode "Rec709" in Nuke. The actual formula is available in Nuke SDK:

r*0.2125 + g*0.7154 + b*0.0721

Arnold's saturation is what's called "Maximum" mode in Nuke, but Arnold has "Luminance' mode in aiColorToFloat - that does exactly the same as the Rec709 formula above. So, mixing it with original node gives us Nuke's Rec709 Saturation.

Thanks me 🙂