I have a binary image, how can I count the balck pixels as a group??

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REZA
REZA 2016-10-30
回答： Image Analyst 2016-10-30
I process a rgb image to gray to binary and use filters to remove noise and get some specific black areas. Now I want to count the areas. How many are there? How can I do that? can anyone help me?

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Walter Roberson
Walter Roberson 2016-10-30
Add a white border around the entire image. Now use regionprops() and ask for EulerNumber
"Returns a scalar that specifies the number of objects in the region minus the number of holes in those objects. "
The number of objects in the region would be 1 (all of the white part together as you have no isolated white areas), so the number you get out would be negative; take 1 minus the number to get the number of black regions.
Or you could invert the binary matrix. After that there would be a number of different approaches, including, for example, asking regionprops for any simple statistic such as Area, and then just counting the number of outputs you get
NumberOfBlackAreas = length( regionprops( ~YourBinaryMatrix, 'Area' ) );
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REZA
REZA 2016-10-30
Hi, thank you for your reply. Can you please explain a little with some code example...As I am new with matlab..
Walter Roberson
Walter Roberson 2016-10-30
cman = imread('cameraman.tif');
YourBinaryImage = cman > 30;
NumberOfBlackAreas = length( regionprops( ~YourBinaryImage, 'Area' ) )

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更多回答（1 个）

Image Analyst
Image Analyst 2016-10-30
You can get it by inverting your image and calling bwlabel:
[labeledImage, numRegions] = bwlabel(~binaryImage);
No need to call regionprops() just to get the count, though you might want to if you want to measure other things like areas.

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