Segmentation of multi-channel(>3) images

[Ankit Agrawal]

Hi everyone,

       I am working on a problem a small step of which requires me to perform segmentation of a multi-channel/multi-band image. That is, like RGB images which are 2D images with 3 channels, I have 2D images with 5 channels. I looked at the segmentation API and it seems to me that all the current implement algorithms work on 2D single channel(grayscale) or/and 2D three channel(RGB). I don't have a thorough knowledge of the implemented segmentation algorithms, so I would like to know if any of them can be extended to multi-channel(>3) images. Thanks.

Regards,
Ankit.

[Juan Nunez-Iglesias]

Hi Ankit,

iirc SLIC was updated to work for any number of channels with `multichannel=True`! Looks like the docstring needs updating! Feel free to submit a PR but in the meantime, give it a shot! =)

Juan.

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[Ankit Agrawal]

Hi Juan,

    Apparently the docs of slic are updated with `multi-channel = True`, but when I tried it for my case, it returned this error -

In [24]: ps = seg.slic(pn, n_segments=100, multichannel=True)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-24-68d7c9154670> in <module>()
----> 1 ps = seg.slic(pn, n_segments=100, multichannel=True)

/usr/local/lib/python2.7/dist-packages/skimage/segmentation/slic_superpixels.pyc in slic(image, n_segments, compactness, max_iter, sigma, spacing, multichannel, convert2lab, enforce_connectivity, min_size_factor, max_size_factor, slic_zero)
    142     if convert2lab and multichannel:
    143         if image.shape[3] != 3:
--> 144             raise ValueError("Lab colorspace conversion requires a RGB image.")
    145         image = rgb2lab(image)
    146

ValueError: Lab colorspace conversion requires a RGB image.

Ankit Agrawal,

IIT Bombay.

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[Juan Nunez-Iglesias]

So... pass convert2lab=False! ;)

[Ankit Agrawal]

Oops...missed it! Thanks.

Ankit Agrawal,

IIT Bombay.

[Stefan van der Walt]

Hi Juan

On 2015-01-15 02:56:28, Juan Nunez-Iglesias <jni....@gmail.com> wrote:
> iirc SLIC was updated to work for any number of channels with
> `multichannel=True`! Looks like the docstring needs updating! Feel
> free to submit a PR but in the meantime, give it a shot! =)

This reminds me--I used SLIC recently to answer a StackOverflow
question, and noticed that not all the parameters are well described.
For example, what is SLIC-0? Would you be willing to review that
docstring for us, especially given that we're using SLIC quite heavily
in our tutorials?

Thanks!
Stéfan