The Foundry NUKE 中的色差

Colour Difference in The Foundry NUKE

所以我试图用 Python 代码直接制作一个绘画节点组,这样我就可以将它用于未来的项目,但我似乎无法从 nuke 中获得公式的力量部分这个色差公式(我也是 Nuke 的新手所以如果有更好的写法请告诉我它会很棒谢谢你,或者如果我完全做错了也请告诉我)

The following formula for color difference is used to create the difference image: |(r1,g1,b1) – (r2,g2,b2)| = ((r1 – r2)^2 + (g1 –g2)^2 + (b1 – b2)^2)^1/2.

nRedShuffle = nuke.nodes.Shuffle()
nRedShuffle['red'].setValue('red')
nRedShuffle['green'].setValue('red')
nRedShuffle['blue'].setValue('red')
nRedShuffle['alpha'].setValue('red')

nGreenShuffle = nuke.nodes.Shuffle()
nGreenShuffle['red'].setValue('green')
nGreenShuffle['green'].setValue('green')
nGreenShuffle['blue'].setValue('green')
nGreenShuffle['alpha'].setValue('green')

#...(so on for the rest of rgba1 and rgba2)

nGreenShuffle2 = nuke.nodes.Shuffle()
nGreenShuffle2['red'].setValue('green')
nGreenShuffle2['green'].setValue('green')
nGreenShuffle2['blue'].setValue('green')
nGreenShuffle2['alpha'].setValue('green')

nBlueShuffle2 = nuke.nodes.Shuffle()
nBlueShuffle2['red'].setValue('blue')
nBlueShuffle2['green'].setValue('blue')
nBlueShuffle2['blue'].setValue('blue')
nBlueShuffle2['alpha'].setValue('blue')

#I am having troubles with the powers below

redDiff = nuke.nodes.Merge2(operation='minus', inputs=[nRedShuffle2, nRedShuffle])
redDiffMuli = nuke.nodes.Merge2(operation='multiply', inputs=[redDiff, redDiff])

greenDiff = nuke.nodes.Merge2(operation='minus', inputs=[nGreenShuffle2, nGreenShuffle])
greenDiffMuli = nuke.nodes.Merge2(operation='multiply', inputs=[greenDiff, greenDiff])

blueDiff = nuke.nodes.Merge2(operation='minus', inputs=[nBlueShuffle2, nBlueShuffle])
blueDiffMuli = nuke.nodes.Merge2(operation='multiply', inputs=[blueDiff, blueDiff])

redGreenAdd = nuke.nodes.Merge2(operation='plus', inputs=[redDiffMuli, greenDiffMuli]) 
redGreenBlueAdd =  nuke.nodes.Merge2(operation='plus', inputs=[redGreenAdd, blueDiffMuli]) 

这里至少有两种方法可以为两个图像实现 Color Difference 公式。您可以在 Merge 节点中使用 difference op,或者您可以在字段中为 MergeExpression 节点中的每个通道编写公式:

每个通道的表达式就这么简单:

abs(Ar-Br)
abs(Ag-Bg)
abs(Ab-Bb)

Python 命令

您可以使用 .nodes.MergeExpression 方法:

import nuke

merge = nuke.nodes.MergeExpression(expr0='abs(Ar-Br)', 
                                   expr1='abs(Ag-Bg)', 
                                   expr2='abs(Ab-Bb)')

或常规 .createNode 语法:

merge = nuke.createNode('MergeExpression')

merge['expr0'].setValue('abs(Ar-Br)')
merge['expr1'].setValue('abs(Ag-Bg)')
merge['expr2'].setValue('abs(Ab-Bb)')

完整代码版本

import nuke
import nukescripts

red = nuke.createNode("Constant")
red['color'].setValue([1,0,0,1])

merge = nuke.createNode('MergeExpression')
merge['expr0'].setValue('abs(Ar-Br)')
merge['expr1'].setValue('abs(Ag-Bg)')
merge['expr2'].setValue('abs(Ab-Bb)')

yellow = nuke.createNode("Constant")
yellow['color'].setValue([1,1,0,1])

merge.connectInput(0, yellow)
nuke.toNode('MergeExpression1').setSelected(True)

nukescripts.connect_selected_to_viewer(0)

# Auto-alignment in Node Graph
for everyNode in nuke.allNodes():
    everyNode.autoplace()

考虑一下! MergeExpression 节点比常规 Merge(difference) 节点 .

慢得多