Simple grain node with with intensity response LUT adjustment.

GrainResponse.nk

Group {
 name GrainResponse
 help "Adds synthetic grain. Push \"presets\" to get predefined types of grain, these are the correct size for 2K scans.\n\nYou can also adjust the sliders to match a sample piece of grain. Find a sample with a rather constant background, blur it to remove the grain, and use as input to this. View with a wipe in the viewer so you can make a match. It helps to view and match each of the red, green, blue separately."
 addUserKnob {20 GrainTab l Grain}
 addUserKnob {3 seed t "Change this value to make different instances of this operator produce different noise"}
 seed 134
 addUserKnob {35 presets l "" -STARTLINE M {"presets/Kodak 5248" "knobs this \{red_size 3.30 green_size 2.90 blue_size 2.5 red_i 0.60 green_i 0.60 blue_i 0.60 red_m 0.42 green_m 0.46 blue_m 0.85 black 0.00 label \{Kodak 5248\}\}" "presets/Kodak 5279" "knobs this \{red_size 2.70 green_size 2.60 blue_size 2.40 red_i 1.00 green_i 0.76 blue_i 0.65 red_m 0.37 green_m 0.60 blue_m 1.65 black 0.00 label \{Kodak 5279\}\}" "presets/Kodak FX214" "knobs this \{red_size 1.87 green_size 2.60 blue_size 2.44 red_i 1 green_i 0.76 blue_i 0.79 red_m 0.41 green_m 0.60 blue_m 1.80 black 0.00 label \{Kodak FX214\}\}" "presets/Kodak GT5274" "knobs this \{red_size 0.04 green_size 0.10 blue_size 0.90 red_i 0.90 green_i 0.76 blue_i 0.81 red_m 0.49 green_m 0.50 blue_m 1.55 black 0.00 label \{Kodak GT5274\}\}" "presets/Kodak 5217" "knobs this \{red_size 0.23 green_size 1.20 blue_size 1.40 red_i 0.60 green_i 0.86 blue_i 0.60 red_m 0.48 green_m 0.42 blue_m 0.87 black 0.00 label \{Kodak 5217\}\}" "presets/Kodak 5218" "knobs this \{red_size 0.10 green_size 1.60 blue_size 1.91 red_i 0.60 green_i 0.86 blue_i 0.73 red_m 0.38 green_m 0.17 blue_m 0.87 black 0.00 label \{Kodak 5218\}\}" presets/other "knobs this \{label other\}"}}
 addUserKnob {26 "" l "@b;Size"}
 addUserKnob {14 red_size l red R 0 100}
 red_size 1.8
 addUserKnob {14 green_size l green R 0 100}
 green_size 1.8
 addUserKnob {14 blue_size l blue R 0 100}
 blue_size 2.2
 addUserKnob {26 "" l "@b;Irregularity"}
 addUserKnob {7 red_i l red}
 red_i 0.6
 addUserKnob {7 green_i l green}
 green_i 0.6
 addUserKnob {7 blue_i l blue}
 blue_i 0.6
 addUserKnob {26 "" l "@b;Intensity"}
 addUserKnob {7 red_m l red t "Amount of grain to add to a white pixel"}
 red_m 0.205
 addUserKnob {7 green_m l green}
 green_m 0.15
 addUserKnob {7 blue_m l blue}
 blue_m 0.285
 addUserKnob {18 black t "Amount of grain to add everywhere"}
 black 0.77
 addUserKnob {6 black_panelDropped l "panel dropped state" -STARTLINE +HIDDEN}
 addUserKnob {18 minimum t "Minimum black level" R 0 0.01}
 minimum {0 0 0}
 addUserKnob {6 minimum_panelDropped l "panel dropped state" -STARTLINE +HIDDEN}
 addUserKnob {26 "" l "@b;Mask"}
 addUserKnob {41 mask_channel l channel t "Choose the channel to use as the mask" T _KEYMIX_.maskChannel}
 addUserKnob {6 use_input_alpha l "use input alpha" t "Use incoming alpha channel to mask the grain application." -STARTLINE}
 use_input_alpha true
 addUserKnob {6 invert_grain_mask l invert -STARTLINE}
 addUserKnob {7 harden_alpha l harden t "Harden the incoming alpha so that grain on motionblurred edges is applied with the correct intensity."}
 harden_alpha 0.75
 addUserKnob {20 LUTTab l Response t "Modify the grain intensity over luminance."}
 addUserKnob {41 lut l "" -STARTLINE T _GrainResponse_.lut}
}
 Input {
  inputs 0
  name InputMask
  label "\[value number]\n"
  xpos -480
  ypos -232
  number 1
 }
 Input {
  inputs 0
  name Input
  label "\[value number]"
  xpos -40
  ypos -232
 }
 Dot {
  name Dot1
  note_font_size 42
  note_font_color 0x7f7f7f01
  xpos -6
  ypos -126
 }
set Nea596140 [stack 0]
 Shuffle {
  red white
  green white
  blue white
  alpha white
  name Shuffle1
  tile_color 0xffffffff
  xpos -260
  ypos -130
 }
set Ne4e82180 [stack 0]
 Copy {
  inputs 2
  from0 -rgba.alpha
  to0 -rgba.alpha
  channels all
  bbox B
  name Copy1
  xpos -480
  ypos -142
 }
push $Nea596140
 Dot {
  name Dot3
  note_font_size 42
  note_font_color 0x7f7f7f01
  xpos -6
  ypos -54
 }
set Nb8ee6cd0 [stack 0]
push $Ne4e82180
 Switch {
  inputs 2
  which {{parent.use_input_alpha}}
  name _USE_INPUT_ALPHA_
  xpos -260
  ypos -58
 }
 Switch {
  inputs 2
  which {{"\[exists parent.input1]"}}
  name _MASK_INPUT_SWITCH_
  xpos -260
  ypos 38
 }
 CCorrect {
  gray 1
  contrast {{1-parent.harden_alpha}}
  name _CONTRAST_ALPHA_
  xpos -260
  ypos 182
 }
 Clamp {
  channels rgba
  name Clamp
  xpos -260
  ypos 230
 }
push $Nb8ee6cd0
 Dot {
  name Dot5
  note_font_size 42
  note_font_color 0x7f7f7f01
  xpos 104
  ypos -54
 }
set Ne651b6e0 [stack 0]
 Dot {
  name Dot4
  note_font_size 42
  note_font_color 0x7f7f7f01
  xpos 214
  ypos -54
 }
 ColorLookup {
  lut {master {curve C 0.01470589638 0.4137254953}
    red {}
    green {}
    blue {}
    alpha {}}
  name _GrainResponse_
  xpos 180
  ypos 134
 }
push $Nea596140
 Dot {
  name Dot2
  note_font_size 42
  note_font_color 0x7f7f7f01
  xpos 324
  ypos -126
 }
 Noise {
  output {rgba.red -rgba.green -rgba.blue -rgba.alpha}
  cliptype none
  replace true
  size {{parent.red_size.w} {parent.red_size.h}}
  zoffset {{frame+seed+red_i/2}}
  octaves 2
  gamma 1
  xrotate {{red_i*45}}
  yrotate {{red_i*45}}
  name red
  xpos 290
  ypos -58
 }
 Noise {
  output {-rgba.red rgba.green -rgba.blue -rgba.alpha}
  cliptype none
  replace true
  size {{parent.green_size.w} {parent.green_size.h}}
  zoffset {{frame+2*seed+green_i/2}}
  octaves 2
  gamma 1
  xrotate {{green_i*45}}
  yrotate {{green_i*45}}
  name green
  xpos 290
  ypos -10
 }
 Noise {
  output {-rgba.red -rgba.green rgba.blue -rgba.alpha}
  cliptype none
  replace true
  size {{parent.blue_size.w} {parent.blue_size.h}}
  zoffset {{frame+3*seed+blue_i/2}}
  octaves 2
  gamma 1
  xrotate {{blue_i*45}}
  yrotate {{blue_i*45}}
  name blue
  xpos 290
  ypos 38
 }
 Add {
  channels rgba
  value -0.5
  name Add1
  xpos 290
  ypos 134
 }
 Multiply {
  channels rgba
  value {{red_m+black} {green_m+black} {blue_m+black} {curve}}
  name Intensity
  xpos 290
  ypos 182
 }
 Merge2 {
  inputs 2
  operation multiply
  bbox B
  name Merge1
  xpos 180
  ypos 231
 }
push $Ne651b6e0
 MergeExpression {
  inputs 2
  expr0 "max( minimum.r, r + Ar )"
  expr1 "max( minimum.g, g + Ag )"
  expr2 "max( minimum.b, b + Ab )"
  channel3 none
  name MergeExpression2
  xpos 70
  ypos 231
 }
push $Nb8ee6cd0
 Keymix {
  inputs 3
  channels rgba
  invertMask {{parent.invert_grain_mask}}
  bbox B
  name _KEYMIX_
  xpos -40
  ypos 230
 }
 Output {
  name Output1
  xpos -40
  ypos 399
 }
end_group