Total area of a region of binary image

Hi every ones I have a question of area of region of binary image.

That mean I have a list of boundary of a region in a image. Use bwboundaries or use bwlabel. Now I want to find there is total how many pixel - areas ( include black and white) in this area ?

I can't use regionprops funtion in matlab because it return only number of black pixel.

Please help me, thanks so much

Answer 1

[Image Analyst]

Huh? Of course you can use regionprops. No need to use bwboundaries() at all, unless you just want to show the outlines of the segmented areas in the overlay above your original gray scale or color image.

If you want the area of all the white pixels in your binary image you can do it two ways, with slightly different results because they use different calculation methods

pixelSum1 = bwarea(binaryImage);
pixelSum2 = sum(binaryImage(:));

If you want the area of each blob in the image individually, you can do it like this:

labeledImage = bwlabel(binaryImage);
measurements = regionprops(labeledImage, 'Area');
allAreas = [measurements.Area];  % List of all the blob areas.
totalAreaOfAllBlobs = sum(allAreas); % Will be the same as pixelSum2

[Tran Tuan Anh]

I think IT's not correct what I mean, I just only want to find the area of one region in image, ( count how many pixel in this region, include white and black pixel in this region, not in image) Please help me

[Image Analyst]

Please show/attach an image. The later code I gave shows you how to how to get the white pixels in a region (blob). To also get the black pixels in only that blob, you'd have to call

binaryImage = imfill(binaryImage, 'holes')

before calling regionprops. That will also count the black pixels in the blob. Obviously if you count all the black and white pixels in the entrie image, that's just the number of pixels in the image, numel(grayImage).

[Tran Tuan Anh]

Thanks you so much.