skimage.feature.peak_local_max behaviour

[Sigmund]

Hi,
My first post a few hours ago somehow didn't appear. It was with examples but I trink I can make my paint without.
If two peaks with the same value are within the min_distance range they are not detectes as too closer and reduced to one. Just use the provided examples in the doc and change the peaks to the same value.

[Sigmund Neher]

Sorry! I realy suck at writing with my cellphone.

--
You received this message because you are subscribed to a topic in the Google Groups "scikit-image" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/scikit-image/HksA6QBButU/unsubscribe.
To unsubscribe from this group and all its topics, send an email to scikit-image...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

[Sigmund]

Since nothing has happened here and I'm back at my office some examples:

normal behavior:

>>> img1 = np.zeros((7, 7))
>>> img1[3, 4] = 1
>>> img1[3, 2] = 1.5
>>> img1
array([[ 0. ,  0. ,  0. ,  0. ,  0. ,  0. ,  0. ],
       [ 0. ,  0. ,  0. ,  0. ,  0. ,  0. ,  0. ],
       [ 0. ,  0. ,  0. ,  0. ,  0. ,  0. ,  0. ],
       [ 0. ,  0. ,  1.5,  0. ,  1. ,  0. ,  0. ],
       [ 0. ,  0. ,  0. ,  0. ,  0. ,  0. ,  0. ],
       [ 0. ,  0. ,  0. ,  0. ,  0. ,  0. ,  0. ],
       [ 0. ,  0. ,  0. ,  0. ,  0. ,  0. ,  0. ]])
>>> peak_local_max(img1, min_distance=1)
array([[3, 2],
       [3, 4]])

>>> peak_local_max(img1, min_distance=2)
array([[3, 2]])


now the, in my opinion, not normal behavior: 

 

>>> img1 = np.zeros((7, 7))
>>> img1[3, 4] = 1
>>> img1[3, 2] = 1
>>> img1
array([[ 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. ,  1. ,  0. ,  0. ],
       [ 0. ,  0. ,  0. ,  0. ,  0. ,  0. ,  0. ],
       [ 0. ,  0. ,  0. ,  0. ,  0. ,  0. ,  0. ],
       [ 0. ,  0. ,  0. ,  0. ,  0. ,  0. ,  0. ]])
>>> peak_local_max(img1, min_distance=1)
array([[3, 2],
       [3, 4]])

>>> peak_local_max(img1, min_distance=2)
array([[3, 2],
       [3, 4]])



Thanks again!

Siggi

[Johannes Schoenberger]

This is not ideal, but please try `skimage.feature.corner_peaks`. It should work with this function (untested).

[Sigmund]

Thanks!

skimage.feature.corner_peaks is working like I expect peak_local_max to do.

Siggi

[Stéfan van der Walt]

On Fri, Jan 16, 2015 at 5:53 AM, Sigmund <sig...@gmail.com> wrote:
> skimage.feature.corner_peaks is working like I expect peak_local_max to do.

Thanks for the feedback, Sigmund. We've been discussing a rewrite of
this functionality exactly because it yields unexpected results like
those you mentioned.

Stéfan