Multiply's tooltip says AB, A if A < 0 and B < 0. Meaning it will Multiply if
either A or B are positive, and keep the A color if they're both negative.
In my tests, I have a +R, -G, -B, and R is multiplied and darkened, but G and B
stay the same.
When RGB are all negative, they all stay the same as A.
If A is positive and B is negative, it still does the multiply. A-R = -0.02,
B-R = .1, Multiply = -.002
You can use an expression to directly handle the math if you want.
set cut_paste_input [stack 0]
version 6.2 v4
push $cut_paste_input
Expression {
expr0 r*r
expr1 g*g
expr2 b*b
name Expression1
selected true
xpos 753
ypos 37
}
--
Chris Glick
--
_____
From: Ben Pierre [mailto:[email protected]]
To: Nuke user discussion [mailto:[email protected]]
Sent: Mon, 13 Jun 2011 10:23:47 -0500
Subject: [Nuke-users] Is Merge(multiply) very wrong?
hey all,
I just plugged the same 3 channel, RGB image to both A & B inputs of a
Merge(A,B) node, set operation to multiply....(ie: image^2).
The image has both positive and negative values.... the result has both
positive and negative values?!
I feel like I've taken crazy pills!.. (I would expect all values to be
positive)..... What kind of "Nuke try and help me out, without me
asking..because I can't help myself" mathematics is going on here?
-Ben Pierre
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