Number of pixels in a threshold image?

I would like to calculate the number of pixels in an image but for the threshold region only. I acquired two channels image (let's say green and red channels). The red channel shows quite lots of background therefore I threshold the image to show me only the pixels between a certain range. Now I'd like to know if there is a way to calculate how many pixel in the threshold, how many pixel in the image in that range.

Thank you

Answer 1

[Guillaume]

It's trivial to do:

pixelcount = nnz(yourimage > yourthreshold)