This is a Python port of Macduff, a tool for finding the Macbeth ColorChecker chart in an image.
The translation to python was done by Andrew Port and was supported by Rare as part of work done for the Fish Forever project.
* An (in-code) parameter `MIN_RELATIVE_SQUARE_SIZE` has been added as a
work-around for an issue where the algorithm would choke on images where
the ColorChecker was smaller than a certain hard-coded size relative to
the image dimensions.
* An optional `patch_size` parameter has been added to give better results
when the approximate (within rtol=25%) pixel-width of the color patches is
known.
* Several additional colorchecker color value options are now included. The
default has been changed to those values provided by xrite for the "passport"
colorchecker.
# if pixel-width of color patches is unknown,
$ python macduff.py examples/test.jpg result.png > result.csv
# if pixel-width of color patches is known to be, e.g. 65,
$ python macduff.py examples/test.jpg result.png 65 > result.csv
Macduff will try its best to find your ColorChecker. If you specify an output image, it will be written with the "found" ColorChecker overlaid on the input image with circles on each patch (the outer circle is the "reference" value, the inner circle is the average value from the actual image). Macduff outputs various useless debug info on stderr, and useful information in CSV-style on stdout. The first 24 lines will be the ColorChecker patch locations and average values:
x,y,r,g,b
The last two lines contain the patch square size (i.e. you can feed another
program this and the location and safely use a square of size with the top
left corner at x-size/2,y-size/2 for each patch) and error against the
reference chart. The patches are output in row order from the typical
ColorChecker orientation ("dark skin" top left, "black" bottom right):
See also: Automatic ColorChecker Detection, a Survey
The original Macduff code is protected under the 3-clause BSD and includes some code taken from OpenCV. See LICENSE.TXT.