[Image-SIG] ImageStat median calculation off?

Bill Janssen janssen at parc.com
Thu Apr 26 20:28:25 CEST 2007

I'm running the following program over a photo:

#!/usr/bin/env python

import sys, os, Image, ImageStat

im = Image.open(sys.argv[1])
im = im.convert("L")
h = im.histogram()
for i in range(len(h)):
    print i, h[i]
s = ImageStat.Stat(h)
print s.mean, s.stddev, s.extrema, s.median
v = max(h)
l = len([x for x in h if (x == v)])
if l > 1:
   print 'Multiple background colors found'
   print 'background gray shade is', h.index(v), '--', v, 'out of', sum(h)

I keep getting different values for "s.median" than I get for "h.index(v)".

Shouldn't they be the same value?  Am I missing something?

This is PIL 1.1.5 with the system Python 2.3.5 on a G4 PowerPC OS X machine.


More information about the Image-SIG mailing list