Inverting linear images

inverting_linearlight.nk

#! Nuke7.0 -nx
version 7.0 v8
Root {
 inputs 0
 name /tmp/inverting_linearlight.nk
 format "2048 1556 0 0 2048 1556 1 2K_Super_35(full-ap)"
 proxy_type scale
 proxy_format "1024 778 0 0 1024 778 1 1K_Super_35(full-ap)"
}
BackdropNode {
 inputs 0
 name BackdropNode1
 tile_color 0xaaaaaa00
 label "Expose wedge"
 note_font_size 25
 xpos -28
 ypos -624
 bdwidth 178
 bdheight 190
}
Constant {
 inputs 0
 channels rgb
 color 0.18
 format "512 512 0 0 512 512 1 square_512"
 name greycard
 xpos -1
 ypos -563
 postage_stamp false
}
Reformat {
 type "to box"
 box_width 96
 filter Impulse
 name Reformat2
 xpos -1
 ypos -535
}
Expression {
 temp_name0 stop
 temp_expr0 "pow(2, 0.125)"
 temp_name1 step
 temp_expr1 "((x/(width-1)*48) * 2) - 48"
 expr0 "r * (stop ** (step))"
 expr1 "g * (stop ** (step))"
 expr2 "b * (stop ** (step))"
 name ExposureWedge
 xpos -1
 ypos -509
 postage_stamp true
}
Crop {
 box {0 0 67.59999847 96}
 reformat true
 crop false
 name Crop1
 label "Crop out >1.0 values because of sRGB used in example"
 xpos -1
 ypos -398
}
Reformat {
 type "to box"
 box_width 512
 box_height 512
 box_fixed true
 name Reformat3
 xpos -1
 ypos -360
}
Dot {
 name Dot1
 label "Perceptively linear ramp"
 xpos 33
 ypos -286
}
Dot {
 name Dot2
 xpos 33
 ypos -253
}
set N5218700 [stack 0]
Expression {
 temp_name0 scanline
 temp_expr0 0
 expr0 "abs(r(x, scanline) - (y/height)) < 1/height"
 expr1 "abs(g(x, scanline) - (y/height)) < 1/height"
 expr2 "abs(b(x, scanline) - (y/height)) < 1/height"
 name Expression4
 label "Plot of \"perceptively linear\" ramp"
 xpos 207
 ypos -263
}
push $N5218700
Invert {
 name Invert4
 xpos -1
 ypos -196
}
set N5374e50 [stack 0]
Expression {
 temp_name0 scanline
 temp_expr0 0
 expr0 "abs(r(x, scanline) - (y/height)) < 1/height"
 expr1 "abs(g(x, scanline) - (y/height)) < 1/height"
 expr2 "abs(b(x, scanline) - (y/height)) < 1/height"
 name Expression3
 label "Plot: mathematically inverted ramp\nLooks \"brighter\" and not a smooth expose ramp"
 xpos 213
 ypos -196
}
push $N5218700
Colorspace {
 colorspace_out sRGB
 name Colorspace3
 xpos -110
 ypos -221
}
Invert {
 name Invert2
 xpos -110
 ypos -195
}
Colorspace {
 colorspace_in sRGB
 name Colorspace4
 xpos -110
 ypos -157
}
Dot {
 name Dot3
 xpos -76
 ypos -115
}
set N7165870 [stack 0]
Expression {
 temp_name0 scanline
 temp_expr0 0
 expr0 "abs(r(x, scanline) - (y/height)) < 1/height"
 expr1 "abs(g(x, scanline) - (y/height)) < 1/height"
 expr2 "abs(b(x, scanline) - (y/height)) < 1/height"
 name Expression1
 label "Plot: Inverted in a perceptively linear space\nLooks as expected"
 xpos 205
 ypos -125
}
push $N7165870
push $N5374e50
push $N5218700
Viewer {
 inputs 3
 frame 1
 input_number 2
 input_process false
 name Viewer1
 xpos -143
 ypos 19
}