How many white pixels in selected pixels?

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Dinuka Ravimal
Dinuka Ravimal on 7 Jun 2020
Edited: Image Analyst on 12 Jun 2020
I'm selecting one particular column and then selecting 100 rows on image. That means I'm extracting 100 pixels from image. Now I want to know how to find how many white pixels (>200 gray value) are in the selected pixels. Could you please write down that code?
clc
clear
% read image
im = imread('6.jpg');
imshow(im)
% convert to gray scale image
imgray = rgb2gray(im);
% size of the gray image
[r,c] = size(imgray);
% ask user to enter column number
fprintf('Column Number Should be between 1 and %d \n',c);
col = input('Please Select a column: ');
% ask user to input starting row number
fprintf('Rows should be bwtween 1 and %d \n',r);
start_row = input('Please Select starting Row Number: ');
% ask user to input ending row number
end_row = input('Please Select ending Row Number: ');
% extracted rows from the column
ext_rows = imgray(start_row:end_row,col);
I want to know how many white pixels (>200 value) in selected pixels?
  3 Comments
Image Analyst
Image Analyst on 7 Jun 2020
Stijn, can you move it down to the official Answers section instead of the comment section which is used for asking for more clarification? You can get "reputation points" if you put it down there, unlike up here, and if Dinuka accepts the answer.

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Answers (1)

KSSV
KSSV on 7 Jun 2020
If A is an array and you want to find how many values > 200 use:
nnz(A>200)

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