## just a question

on 29 May 2012

### Image Analyst (view profile)

let's say i have the image:
img =
[1 0 -1;
0 -1 0;
1 1 -1];
and I'd like to get the values on the 8-connected area around the center:
vals = [0 -1 0 1 0 1 1 -1];
and then get the most common and least common values, and if there are two, to pick the lowest value.
I can only thing to do:
meh = im2col(img,[3 3],'distinct');
meh(5,:) = [];
but i can't figure out a way to get the least common thing unless i do ~mode a bunch of times...
Any ideas? Thanks :)

### Image Analyst (view profile)

on 29 May 2012

You could use blockproc and have the blockproc function call hist. But you know that there could be up to 8 values that are the least common. What if your 8 neighbors are 8 unique values? What do you want to do then?

Teja Muppirala

### Teja Muppirala (view profile)

on 29 May 2012
Also, check out NLFILTER. It's similar to BLOCKPROC, but for this specific problem I think the syntax might be a little simpler
Image Analyst

### Image Analyst (view profile)

on 29 May 2012
Yes, you could do the same thing with nlfilter and it is easier to understand. Good point.
Stephen

### Stephen (view profile)

on 4 Jun 2012
yeah, but you asked if all values were unique, what would happen. It should order from lowest to highest and return the extremes. Thanks Teja, I'll check out nlfilter