Invert/negate color?

[AndydeCleyre]

Hello, and thanks!

I don't understand much of color theory, but am trying to figure out where what I think of as "invert" or "negate" fits in to the functions provided by pastel.

My first guess was to rotate 180, but now think that that's equivalent to complement, which isn't the negation effect I'm seeking.

Can you provide any insight on color negation/inversion, as it relates to pastel's features?

Thanks!

[sharkdp]

Are you maybe thinking negative in the sense of https://en.wikipedia.org/wiki/Negative_(photography)? I'm not sure if there is a principle theory behind that. You probably want to turn black to white? So maybe something like complement, but then also an inversion of the lightness channel?

[AndydeCleyre]

Yes, I think so. Some examples of the effect I'm after:

• Plasma desktop's effect: Invert
• ImageMagick's option to convert: -negate
• GIMP's Colors>Invert
• Krita's Filter>Adjust>Invert
• Photopea's Image>Adjustments>Invert