MATLAB: How to calculate the area of different labels and remove the labels with smaller area?

Question

i labeled an image using CC = bwconncomp(BW).how to find area of different labels?? and how do i remove labels with smaller area???

Answer 1

CC is a struct including the field PixelIdxList. If you define the area as number of pixels, you just need the number of elements of each cell:

 elemsize=cellfun(@numel,CC.PixelIdxList);

To remove the small ones (I define "small" as "less than 100 pixels"):

 BW2=BW;
 BW2(vertcat((CC.PixelIdxList{cellfun(@numel,CC.PixelIdxList)<100})))=0;

You can of course do this without copying BW (just ignore the first line and use BW instead of BW2 in the second line).

Edit: If you also want to remove these from CC:

 CC.PixelIdxList(cellfun(@numel,CC.PixelIdxList)<100)=[];
 CC.NumObjects=numel(CC.PixelIdxList);