Scikit-image: RuntimeWarning in blob.py (division by zero)

[emmanuelle]

see for example the warning in https://scikit-image.org/docs/dev/auto_examples/features_detection/plot_blob.html#sphx-glr-auto-examples-features-detection-plot-blob-py

The warning is initiated in the _blob_overlap function.

Also mentioned in the forum https://forum.image.sc/t/runtime-warning-with-blob-detection-when-threshold-is-too-low/37965

[imagesc-bot]

This issue has been mentioned on Image.sc Forum. There might be relevant details there:

https://forum.image.sc/t/runtime-warning-with-blob-detection-when-threshold-is-too-low/37965/5

[emmanuelle]

Oh this imagesc-bot is nice :-).

[dsandeep0138]

@emmanuelle when sigma of both the blobs are 0 (i.e., radius of blobs = sqrt(2) * sigma = 0) we can return the _blob_overlap as 0.0 right? Please check below which would resolve the issue and let me know your comments.

if blob1[-1] == 0 and blob2[-1] == 0:
    return 0.0
elif blob1[-1] > blob2[-1]:
    max_sigma = blob1[-sigma_dim:]
    r1 = 1
    r2 = blob2[-1] / blob1[-1]
else:
    max_sigma = blob2[-sigma_dim:]
    r2 = 1
    r1 = blob1[-1] / blob2[-1]

[jni]

@dsandeep0138 I think that fix would work! If you could open a PR (including a test), that would be wonderful!