# how to find the number of pixels in the white region of a binary image

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Rah Ul on 3 Jul 2022
Answered: Image Analyst on 3 Jul 2022
I want to get the number of pixels o the white area in the given binary image. is there any code available to know tha same. The ultimate need is to find the area of the region by multiplying number of pixels with area of one pixel

Raghav on 3 Jul 2022
Edited: Jan on 3 Jul 2022
As white pixels have a value=1 (and black pixels' value=0), doing sum of pixel values can return the total number of white pixels in the binary image. If Image is stored in "Im", you can write the expression:
WhiteNum=sum(Im(:));
If you want to find the area of object formed by white pixels, use the function - bwarea().
To understand more about bwarea(), refer to the link that I am attaching below:

Image Analyst on 3 Jul 2022
You can use nnz or bwarea
Note they give different counts. nnx is strictly a count of the number of pixels. bwarea weights the counts by the shape of the boundary.
binaryImage = [0,1;1,1]
binaryImage = 2×2
0 1 1 1
numWhite = nnz(binaryImage)
numWhite = 3
area = bwarea(binaryImage)
area = 3.1250

R2021a

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