How to find average pixel value of an grayscale image in c++?

asked Aug 4 '18

Samjith888
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I'm going to classify the image into black or not. So i have to find the average pixel value of the image..

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~~really ??? please explain, why you think, you need the average for this.~~

berak (Aug 4 '18)edit

If the average will be lesser than a specific value (eg: 100) then i can realize that this image has more black shades and i can classify this.If its like 0 to 30 then i can consider it as black image in humans view.

Samjith888 (Aug 4 '18)edit

Do you know any other method to find whether the image is black or not?

Samjith888 (Aug 4 '18)edit

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answered Aug 4 '18

berak
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we can use:

Scalar m = cv::mean(img);
Mat bin = img > m[0]; // syntax sugar for 'threshold()'

but better, opencv has an automatic threshold method:

Mat bin;
cv::threshold(img, bin, 0, 255, THRESH_OTSU);

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Yeah. It works. Thank you..

Samjith888 (Aug 6 '18)edit

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Asked: Aug 4 '18

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Last updated: Aug 04 '18

How to find average pixel value of an grayscale image in c++? edit savecancel

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How to find average pixel value of an grayscale image in c++?