Help, I'm going mad with this

[Peter Otten]

azrael wrote:

> Help, I'm going mad with this

Is "Otsu threshold algorithm" to boring as a subject?

> Meanwhile I tried about 5 different implementations of the otsu
> threshold algorithm. I'll go mad.
> Please help me. I don't know what to do. I even tried to implement it
> from c and java, but no way. nothing.
> I've been reading about 5 ppt presentations and 4 pdf's and I failed.
> Can someone look at this code.
> If needed I can paste 3 other codes.

Hmm, you just learned that quality is more important than quantity then.
Choose the text that seems most accessible while still complete and try to
understand it.

> if __name__=="__main__":
>     otsu(histogram)

You are using a parameter before defining it. It seems you have not yet
groked the basics of cut and past then.

>     histogram= [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
> 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
> 0, 0, 0, 0, 0, 0, 0, 1, 0, 2, 0, 0, 2, 1, 2, 0, 1, 3, 3, 3, 3, 1, 3,
> 1, 3, 5, 2, 3, 3, 3, 6, 3, 4, 5, 4, 9, 6, 11, 6, 10, 3, 11, 9, 9, 12,
> 22, 18, 34, 22, 28, 32, 25, 34, 38, 34, 54, 65, 106, 160, 167, 203,
> 282, 364, 446, 637, 816, 1022, 1264, 1456, 1646, 1753, 1845, 1922,
> 2203, 2231, 1973, 2245, 2369, 2349, 2258, 2130, 2066, 1835, 1640,
> 1554, 1414, 1179, 1024, 974, 938, 838, 785, 756, 803, 921, 952, 865,
> 722, 625, 608, 547, 498, 412, 438, 408, 413, 415, 339, 366, 330, 320,
> 293, 315, 368, 411, 434, 500, 531, 538, 552, 665, 811, 869, 998, 1021,
> 1075, 1080, 1030, 934, 926, 1074, 942, 941, 1014, 1440, 2966, 5301,
> 2729, 3400, 5563, 13096, 9068, 6045, 2813, 686, 180]
> 
> 
> Well, this list is a example list that i have exported. for this list
> the result the threshold should be at 218.

If you need the result and don't want to bother with understanding the
algorithm -- I found an implementation in C via Google Codesearch 

http://www.google.com/codesearch?hl=de&q=+otsu+threshold+show:3rXPo8eEzw0:z-1MzowD-bQ:cDGSVzqKA7M&sa=N&cd=1&ct=rc&cs_p=http://www.studio-to-go.co.uk/source-packages/2.x/gocr-0.41.tar.bz2&cs_f=gocr-0.41/src/otsu.c#a0

It gives the desired result if you use the line that is commented out

// orig: sb ...

instead of its current replacement. Translation to Python should be
straightforward, but you can ask on c.l.py if you run into problems.

Peter