MATLAB: MATLAB detecting the largest open space in a binary image

area of largest black spacebinary imageImage Processing Toolboxregionprops

I am trying to obtain the area of the largest open (black) space (non-contiguous) in a binary image. The actual binary image is shown in "Original_Image.png" attachment. What I am looking for is the area of the region roughly bounded by the red line in the "Original_Image_red.png". Thanks for your help.

Best Answer

You didn't attach the image. But the steps are (untested)
% Call bwlabel or bwconncomp on the inverted image.
cc = bwconncomp(~binaryImage);
% Measure the area of all the blobs.
measurements = regionprops(cc, 'Area');
allAreas = [measurements.Area]
% Find the biggest area and blob number
[maxArea, indexOfBiggestBlob] = max(allAreas);
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