need an expression for green spill supress

[raj_raj85]

hi,
Is there any expression for green spill supress that i can write into the 'expression node'?
thanks,
raj.:fingerscr

[sdinozzi]

g > (r+b)/2 ? (r+b)/2 : g

put that in the expression field for the green channel.
(also could be modified for a blue suppress.. b > (r+g)/2 ? (r+g)/2 : b)

-Steve

[raj_raj85]

hey thanks steve that really worked..!

[Gentle Fury]

http://eastoflapost.com/East_of_LA_Post/Gizmos_files/DeSpill.gizmo.zip

Thats my despill gizmo with a drop down for green or blue and a slider :)

[lukesan79]

g > (r+b)/2 ? (r+b)/2 : g

put that in the expression field for the green channel.
(also could be modified for a blue suppress.. b > (r+g)/2 ? (r+g)/2 : b)

-Steve

Hi!
nice exp :D
But what about that "?" in the middle? Is it some kind of condition?

[mreithoffer]

if g is > then (r+b)/2 use (r+b)/2, else use g

http://www.vfxtalk.com/forum/nuke-create-if-statement-nukes-expression-node-t17068.html

[Gentle Fury]

nice math, I like that.

[lukesan79]

if g is > then (r+b)/2 use (r+b)/2, else use g

http://www.vfxtalk.com/forum/nuke-create-if-statement-nukes-expression-node-t17068.html

Thanks man, useful!
Is it the color difference math?

[Gentle Fury]

Thanks man, useful!
Is it the color difference math?

No, it's an average if red and blue.

More accurately it's saying that if the per pixel value the green channel exceeds the per pixel average value of red and blue then use the average of red and blue, otherwise leave it alone.

[lazylorcan]

where exactly does this go in the expression node?

[lazylorcan]

ah no worries, i got it.

very nice results btw

[tangqiang]

you can simply use 'g=min(g,(r+b)/2)'
same result