Negative Film Mask Removal Tool

Automatically remove color mask from camera raw film scans.

Quick Start

Process order.

stages = [
    RawLoadStage("LoadRAW"),
    BorderExtractStage("BorderExtract"),
    ColorClassifyStage("ColorClassify"),
    WhiteBalanceComputeStage("WBCompute"),
    WhiteBalanceApplyStage("WBApply"),
    InvertStage("Invert"),
    LevelRegionSelectStage("LevelRegionSelect"),
    LevelAdjustStage("LevelAdjust"),
    ToneAdjustStage("ToneAdjust"),
]

1. black/white point auto tune by threshold first
2. overwrite with specific black/white if --tone-white, --tone-black, --level-white-point is not None

• download a camera raw

• run:

python cast_off.py ./RAW.dng --border u0.02 --level-pixel-threshold 0.0001  --wb-ix 4,3 --debug --visualize  --tone-pixel-threshold 0.02  --center-ratio 0.8 --tone-black 37000

• get vis like:

• output:

Save preset

python cast_off.py ./ZFC_5837.NEF --border l0.1,r0.1 --level-pixel-threshold r0.001,g0.001,b0.03  --wb-ix 4,1 --debug --visualize  --tone-pixel-threshold 0.03  --tone-white 64000 --level-white-point "b61000" --save-preset ./preset.pkl

Load preset

python cast_off.py ./ZFC_5837.NEF --load-preset ./preset.pkl -o "new_{name}.png"

Processing Pipeline

1. White Balance: Compute white balance from border area, apply to entire image
   • Classify border pixels into clusters by brightness
   • Select specific clusters for white balance calculation
   • --wb-ix 4,0,1 means 4 clusters, select [0, 1] to compute wb.
2. Invert: Invert all 3 RGB channels (negative to positive)
3. Level Adjustment: Redefine black and white points
   • Automatically calculate percentile threshold for each channel
4. Luminance Adjustment
   • Set black/white point from [0, 65535]