How to calculate the area of only white part in the image

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kanika bhalla
kanika bhalla 2021-4-22
评论： kanika bhalla 2021-4-23
I want to calculate the area of only white part as shown in the figure. I had used - bwarea(image). But I am not sure whether its calculating correct area or not. As I just need the white portion area.
Any help is much appreciated.
Thank you in advance!!
  2 个评论
Jonas
Jonas 2021-4-22
you could count the white pixels, divide it by overall number of pixels and multiply it with the real size of the image
kanika bhalla
kanika bhalla 2021-4-22
Hi Jonas,
Thank you for your answer. But I need some automatic way to calculate the area of white portion. Any help related to this is much appreciated.
Thank you!!

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采纳的回答

Image Analyst
Image Analyst 2021-4-23
You simply use nnz on your binary image to get the area in pixels
whiteArea = nnz(mask)
or you could use bwarea() - it uses a somewhat different algorithm for determining area (it's not just counting pixels).
whiteArea = bwarea(mask)
  1 个评论
kanika bhalla
kanika bhalla 2021-4-23
Hi Image Analyst,
Thank you for introducing me to new function- nnz
As i have checked doc nnz. n = nnz(MASK). It returns the number of nonzero elements in matrix X. I have confusion then how it will calculate the area.
Now I have used bwarea() to calculate the area of white portion.
Thank you for your useful answers and help!!

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更多回答（1 个）

Stephan
Stephan 2021-4-22
编辑：Stephan 2021-4-22
Same as in your question yesterday: regionprops will solve both problems in 1 line of code.
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kanika bhalla
kanika bhalla 2021-4-23
Hi Stephan,
Thank you for your help.
I tried what you guided me as shown below.
M=imread('C:\Users\Ucl\Desktop\test\mask_14H14\groundtruth_for_metrics\129groundtruth.jpg');
cc = bwconncomp(M);
stats = regionprops(cc,'Area');
But this is not giving me teh one desired output. Could you please guide me further why the output looks like this. I should get one area of only white portion.
Thank you!!

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