What would I do to get the negative Color3/BrickColor of something?

local function returnneg(colorval)
	return Color3.new(1-colorval.r, 1-colorval.g, 1-colorval.b) --returns a color3 value thats where numbers are from 0 to 1 but its the opposite
	--to get the specific color use .r, .g, .b, and it will turn it to 1-0 automatically so by taking away from one it will be opposite
end
local base = Color3.fromRGB(100,250,30) --green , goes to purple
local negbase = returnneg(base)
workspace.Baseplate.Color = base
wait(3)
workspace.Baseplate.Color = negbase

basically using 1 to make it negative and a function to return it. (returnneg(base) , base can be Color3.new , Color.fromRGB ect)
EDIT : This is just an example of how you would implement it. e.g:

local function returnneg(colorval)
	return Color3.new(1-colorval.r, 1-colorval.g, 1-colorval.b)
end
local base = mouse.Target.Color
local negbase = returnneg(base) --basically saying local negbase = Color3.new(opposite color)
mouse.Target.Color = negbase