soft-matter/trackpy — pull request #72 by danielballan (2014-02-08 20:20:18+00:00)
Title: ENH/TST: Warn user if image looks like color (has 3 or 4 in its shape).

In [2]: image = imread('becca_testimage.tif')

In [3]: image.shape
Out[3]: (250, 250, 4)

In [4]: f = tp.locate(image, 21)
UserWarning: I am interpreting the image as 3-dimensional. If it is actually a 2-dimensional color image, convert it to grayscale first.