Plot Scanline

Those who used to use Plot Scanline in Shake are probably missing this from Nuke. I am. I use it for all sorts of things, mainly for explaining color correction theory to students, but also for color gauging. It’s a handy tool.

For those  who aren’t familiar with it, it’s similar to the histogram image we recognize from Nuke and Adobe effects. But I don’t want this as an effect, just as a viewing tool.

So I opened up Nuke’s Expression node and for the first real time started really exploring it, and here we go, a Plot Scanline node. Hook anything up and choose a line by using the ‘line’ knob in the User tab, and it will give you the pixel values of the pixels in that line as a graph. It will work between 0 and 1. Anything above it will be out of frame, unless you use the ‘mult’ knob in the User tab.

I’ll wrap it up better and post it up in Nukepedia, but until then, here is something to play with (copy and paste into Nuke):


set cut_paste_input [stack 0]
version 6.0 v5
push $cut_paste_input
Reformat {
type "to box"
format "256 256 0 0 256 256 1 square_256"
box_width 256
box_height 256
box_fixed true
name Reformat1
selected true
xpos 181
ypos -71
}
Ramp {
p0 {0 0}
p1 {{width i} 0}
name Ramp1
selected true
xpos 181
ypos -47
}
Grade {
white {1.399999976 0.5600000024 1 1}
gamma {0.6100000143 1.320000052 0.6499999762 1}
name Grade1
selected true
xpos 181
ypos -23
}
Expression {
expr0 "y==floor(r(x, pos.y)*height*mult)?1:0"
expr1 "y==floor(g(x, pos.y)*height*mult)?1:0"
expr2 "y==floor(b(x, pos.y)*height*mult)?1:0"
channel3 alpha
name PlotScanline
selected true
xpos 181
ypos 32
addUserKnob {20 User}
addUserKnob {12 pos}
addUserKnob {7 mult R 0 5}
mult 1
}

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