vision local threshold sauvola selects weird sections of background

[smithed]

 Hi, I'm trying to use the local thresholding feature. For my particular image, niblack doesn't work that well but the sauvola and modified do -- except that it selects a huge swath of the background. Not the whole background, though, which is odd. 

The image itself is obviously made up but is a representation of what I want to select (the triangles). The raw image is at the bottom. Any ideas on why its selectively picking a column of background out of the image? Any ideas on how to remove that section?

For comparison, in this simplified image Niblack works fine. I basically want the goodness of the sauvola without the weirdness.

[ARVega]

Hello there!

I think you could use another function once you get your binary image from that to get rid of the big perimeter area. It is called "Particle filter", it is on the "Binary" processing functions tab.

Here is a screenshot of what I did:

[smithed]

Ah yes, you're right. Thats seems like a reasonable way to get rid of that ring. Thanks.

[ARVega]

You are very welcome! please consider marking this post as solved, as your question has been addressed.