How to count the number of pixels with a certain pixel value in python opencv?

Question

I'd like to count the number of pixels with the value=[0,100,234] in an image.

Without using loops over the image, could you please propose a method of how to determine the number of these particular pixels?

Thanks, I checked this one already, but could not make it work with countNonzero function... — Kristan
– Kristan, Commented Feb 15, 2017 at 16:56
could not make it work with countNonZero ... why? What's the problem? @Namorim link is correct. You can alternatively get the length of the list returned by (something like): np.where((image == [0, 100, 234]).all(axis = 2)) — Miki
– Miki, Commented Feb 15, 2017 at 17:21
SOrry, I dont get it...how to you proceed then to count the pixels? — Kristan
– Kristan, Commented Feb 15, 2017 at 17:35

Miki · Accepted Answer · 2017-02-17 12:05:28Z

9

To count the number of pixels with the value = [0,100,234] you can use:

np.count_nonzero((img == [0, 100, 234]).all(axis = 2))

answered Feb 17, 2017 at 12:05

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1 Comment

np.count_nonzero(img == value) can be used in the grayscale case