Color Transfer in Python

Three methods of color transfer implemented in python.

Examples

input img | reference img | mean std transfer | lab mean std transfer | pdf transfer + regrain

Clone

• install git-lfs

yum install git-lfs

• clone

git clone https://github.com/pengbo-learn/python-color-transfer.git

Environment

• python3
• install dependency by sh env.sh.

# env.sh
pip3 install opencv-python==4.2.0.34
pip3 install numpy==1.19.3

Run

# python demo.py 
/root/python_color_transfer/imgs/scotland_house.png: 361x481x3
/root/python_color_transfer/imgs/scotland_plain.png: 361x481x3
pdf transfer time: 0.67s
regrain time: 0.49s
mean std transfer time: 0.04s
lab mean std transfer time: 0.22s
save to /root/python_color_transfer/imgs/scotland_display.png

/root/python_color_transfer/imgs/house.jpeg: 512x768x3
/root/python_color_transfer/imgs/hats.png: 512x768x3
pdf transfer time: 1.47s
regrain time: 1.16s
mean std transfer time: 0.09s
lab mean std transfer time: 0.09s
save to /root/python_color_transfer/imgs/house_display.png

/root/python_color_transfer/imgs/fallingwater.png: 727x483x3
/root/python_color_transfer/imgs/autumn.jpg: 727x1000x3
pdf transfer time: 1.87s
regrain time: 0.87s
mean std transfer time: 0.12s
lab mean std transfer time: 0.11s
save to /root/python_color_transfer/imgs/fallingwater_display.png

/root/python_color_transfer/imgs/tower.jpeg: 743x1280x3
/root/python_color_transfer/imgs/sunset.jpg: 743x1114x3
pdf transfer time: 2.95s
regrain time: 2.83s
mean std transfer time: 0.23s
lab mean std transfer time: 0.21s
save to /root/python_color_transfer/imgs/tower_display.png

Methods

Let input image be I, reference image be R and output image be O.
Let f{I}(r, g, b), f{R}(r, g, b) be probability density functions of I and R's rgb values.

• mean std transfer

  O = (I - mean(I)) / std(I) * std(R) + mean(R).

• lab mean transfer

  I' = rgb2lab(I),
  R' = rgb2lab(R),
  O' = (I' - mean(I')) / std(I') * std(R') + mean(R'),
  O = lab2rgb(O').

• pdf transfer

  O = t(I), where t: R^3-> R^3 is a continous mapping so that f{t(I)}(r, g, b) = f{R}(r, g, b).

References

• pdf transfer
  Automated colour grading using colour distribution transfer by F. Pitie , A. Kokaram and R. Dahyot.
  Author's matlab implementation

• lab mean transfer
  Color Transfer between Images by Erik Reinhard, Michael Ashikhmin, Bruce Gooch and Peter Shirley.
  Open source's python implementation