MATLAB: Calling function for blockproc

blockprocbox countingcalling function

I want to create a calling function for blockproc, where I obtain the number of connected objects inside each block of the image. B1 is my image, a logical returned after converting my image to black and white based on a threshold. The relevant code is here:
    func = @blockfun 
    blockSize = [16 16];
    blockyImage8 = blockproc(B1, blockSize, func);
And the function is here:
    function x = blockfun(a)
    CC = bwconncomp(a,8);
    x = CC.NumObjects;
    end
I get the error message:
Error using bwconncomp
Expected input number 1, BW, to be one of these types:
logical, double, single, uint8, uint16, uint32, uint64, int8, int16, int32, int64
Instead its type was struct.
Any advice?

Best Answer

As its help explains, blockproc supplies a structure to the called function. The fields of the structure are listed in the help. Possibly you want the data field:

CC = bwconncomp(a.data,8);
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