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### How to create a binary image mat?

Whats the right way to create a binary image?

I'm trying to convert an ordinary image mat to grayscale and apply a threshold afterwards like this:

// first convert the image to grayscale
cvtColor(imageMat, grayscaleMat, CV_RGB2GRAY);

// then adjust the threshold to actually make it binary
threshold(grayscaleMat, binaryMat, 100, 255, CV_THRESH_BINARY);


Shouldn't that create a mat that does only have 0s and 255s (as uchars) in it? At least that's how I understand it. Unfortunately, its not only 0s and 255s.

What am I doing wrong?

Thanks a lot!