Number of dark stripe in a image

How can I calculate number of black or gray stripe in the above region using Matlab (not by counting then manually)?

Answer 1

[Nathan Hardenberg]

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.

[Amrit Kumar Mondal]

Dear Hardenberg,

Thank you for your suggestion.

Can you please help me, How to take line scan along x direction?

[Nathan Hardenberg]

Here is some example code, that works if the image has no noise:

imageRGB = imread(".\myfolder\1.png");
imageGray = rgb2gray(imageRGB);  % convert to grayscale (if necessary)

n = 2  % Linenumber to analyse
line = imageGray(n, :)

minima = islocalmin(line)

nrOfBlackLines = sum(minima)

[Amrit Kumar Mondal]

Thank you for your help.

I am using Matlab R2017a and I have attached one error for the code. Here, islocalmin() command is not working.

[Nathan Hardenberg]

You could use the findpeaks()-function and negate your signal to find the minimas

minima = findpeaks(-single(line))

[Amrit Kumar Mondal]

Thank you Hardenberg.