I would extract one line of pixels in the image and then use the islocalmin() or islocalmax()-function. This searches for local minima/maxima. Depending on counting black or white stripes (to count black you need islocalmin()).
Then you just need to check the length of the vector.
If you have Problems (e.g. finding multiple maxima/minima in one stripe) check the documentation for possible arguments which could resolve possible issures.
Note that this only works if your stripes are always "clean". If not possible filtering beforehand might be nessescary.
