Hello all,

actually, local_maxima should be equivalent to h-maxima, with h=1

h-maxima (and also local_maxima) give non ponctual locations. There might be a need for a function of ultimate erosion. Does it exist somewhere ?

I totally agree with you, the official watershed demo should be modified.

Yann GAVET
Assistant Professor - Ecole des Mines de Saint-Etienne
158 Cours Fauriel, 42023 Saint-Etienne cedex 2, FRANCE
Tel: (33) - 4 7742 0170


On 04/12/2018 09:08 AM, imag...@sina.com wrote:
Hi,everyone

I think we should not use peak_local_max for find watershed's seeds. why not use h_maxima? which can give a h tolerance. I think if we should replace it in the official demo? It would cause a misunderstanding.

And scikit-image's h_maxima, h_minima is very slow. here I implements one with numba, https://github.com/Image-Py/imagepy/blob/master/imagepy/ipyalg/hydrology/findmax.py. you can see if it is useful.

yxdragon
----- 原始邮件 -----
发件人:Stefan van der Walt <stef...@berkeley.edu>
收件人:"Mailing list for scikit-image (http://scikit-image.org)" <scikit-image@python.org>
主题:Re: [scikit-image] local maxima improvements
日期:2018年04月12日 03点08分


On Wed, 11 Apr 2018 12:44:45 +1000, Juan Nunez-Iglesias wrote:
 > In [7]: image
 > Out[7]:
 > array([[ 0.,  0.,  0.,  0.,  0.,  0.],
 >        [ 0.,  1.,  0.,  0.,  0.,  0.],
 >        [ 0.,  0.,  0.,  0.,  0.,  0.],
 >        [ 2.,  2.,  2.,  4.,  4.,  2.],
 >        [ 2.,  2.,  2.,  4.,  4.,  2.],
 >        [ 2.,  2.,  2.,  2.,  2.,  2.]])
 >
 > In [15]: feature.peak_local_max(image)
 > In [17]: image_peak[tuple(feature.peak_local_max(image).T)] = 1
 >
 > In [18]: image_peak
 > Out[18]:
 > array([[ 0.,  0.,  0.,  0.,  0.,  0.],
 >        [ 0.,  1.,  0.,  0.,  0.,  0.],
 >        [ 0.,  0.,  0.,  0.,  0.,  0.],
 >        [ 0.,  1.,  0.,  1.,  1.,  0.],
 >        [ 0.,  1.,  0.,  1.,  1.,  0.],
 >        [ 0.,  0.,  0.,  0.,  0.,  0.]])
That output in column 1 looks highly suspect! This is a great example
for a regression test, thanks Yann.
Stéfan
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