Get the percentage of dark spots

I want measure the percentage of patches in the stick. I already find the patches but I cannot find the how many patches are selected (red color spots).

Below is my code. Please help to find the count.

Img=imread('Images\IMG_5058.jpg');
      Gimg=rgb2gray(Img);
      figure(1);imshow(Gimg);
      figure(2);imshow(Img);
      %grey point less than 95
      BW=Gimg<95;
      %Find Weighted Centroid of the chosen dots and plot them together with original image
      rp=regionprops(BW,Gimg,'WeightedCentroid');
%       disp(rp);
      n=numel(rp);
       disp(n);
         for j=1:n
             Position(j,1)=rp(j).WeightedCentroid(1); 
%              disp(Position(j,1));
             Position(j,2)=rp(j).WeightedCentroid(2);
%              disp(Position(j,2));
         end
         for i=1:n-1
         if  (Position(i+1,1)-Position(i,1))<5 || (Position(i+1,2)-Position(i,2))<5
             Position(i+1,1)=1/2*(Position(i,1)+Position(i+1,1));
             Position(i+1,2)=1/2*(Position(i,2)+Position(i+1,2));
             Position(i,1)=0;Position(i,2)=0;
         end
         end
    [m,n]=size(Position);
%     fprintf('%d - %d\n', m,n);
    figure(3);imshow(Img); axis image; hold on;
    lunt=0;
        for i=1:m
          for j=1:n-1
          arr(:, j) = plot(Position(i,j),Position(i,j+1),'r*')
%           plot(x(idx),y(idx),'r','linewidth',3)
%           display(arr);
          end
          end
%   fprintf('%d - %d\n', m,n);       
      for x=1:Position
            fprintf('%d\n', Position(:,x));
            lunt = lunt+1;
            fprintf('Patch count = %d\n', lunt);
      end      
     sizeP = length(Position);
%      fprintf('%d\n', Position);
     Position(all(Position==0,2),:)=[];
     display(Position);
%      fprintf('%f\n', Position);
%      Position = Position*2;
     fprintf('count = %d\n', lunt);
     fprintf('%d\n', pastCount);

Answer 1

[Image Analyst]

Try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 15;

baseFileName = 'IMG_5058.JPG';
fullFileName = fullfile('Images', baseFileName);
Img=imread(fullFileName);
Gimg=rgb2gray(Img);
figure(1);imshow(Gimg);
figure(2);imshow(Img);
%grey point less than 95
BW=Gimg<95;
%Find Weighted Centroid of the chosen dots and plot them together with original image
rp=regionprops(BW,Gimg,'WeightedCentroid');
%       disp(rp);
n=numel(rp);
disp(n);
for j=1:n
	Position(j,1)=rp(j).WeightedCentroid(1);
	%              disp(Position(j,1));
	Position(j,2)=rp(j).WeightedCentroid(2);
	%              disp(Position(j,2));
end
for i=1:n-1
	if  (Position(i+1,1)-Position(i,1))<5 || (Position(i+1,2)-Position(i,2))<5
		Position(i+1,1)=1/2*(Position(i,1)+Position(i+1,1));
		Position(i+1,2)=1/2*(Position(i,2)+Position(i+1,2));
		Position(i,1)=0;Position(i,2)=0;
	end
end
[m,n]=size(Position);
%     fprintf('%d - %d\n', m,n);
figure(3);imshow(Img); axis image; hold on;
lunt=0;
spotCount = 0;
for i=1:m
	for j=1:n-1
		arr(:, j) = plot(Position(i,j),Position(i,j+1),'r*');
		%           plot(x(idx),y(idx),'r','linewidth',3)
		%           display(arr);
		spotCount = spotCount + 1;
	end
end
%   fprintf('%d - %d\n', m,n);
for x=1:Position
	fprintf('%d\n', Position(:,x));
	lunt = lunt+1;
	fprintf('Patch count = %d\n', lunt);
end
sizeP = length(Position);
%      fprintf('%d\n', Position);
Position(all(Position==0,2),:)=[];
display(Position);
%      fprintf('%f\n', Position);
%      Position = Position*2;
fprintf('Spot count = %d\n', spotCount);
fprintf('lunt = %d\n', lunt);

You get:

Spot count = 3089

lunt = 0

[Chathurika Sandamali]

@Image Analyst Thank you for your answer and I have another question.

How can I put this 246 to a variable. (Below is appeared execute this code. display(Position);)

[Image Analyst]

Not sure what you mean. It looks like Position is already a variable. Why do you want a different one? If you do, simply copy it

positionCopy = Position;

[Chathurika Sandamali]

Position is an array. It contain several values. But I want to get only 246 to another variable.

[Image Analyst]

If it has more than 246, which 246 do you want? The first 246 rows?

first246Rows = Position(1:246, :);

[Chathurika Sandamali]

Thank you very much @Image Analyst. I wanted to find number of rows. But I don't know it is rows. Now I found, it in the word 'rows' in your previous comment. Thak you for your help.

[Image Analyst]

You can do

[rows, columns] = size(Position)

[Chathurika Sandamali]

I did that. Thank you. @Image Analyst

Answer 2

[darova]

Use first matrix of an image (red channel)

A0 = imread('image.png');
A1 = ~im2bw(A0,0.8);        % select the stick
A2 = A0(:,:,1) > 210;       % select red dots and background
R = A1 & A2;                % red dots
P = sum(R(:))/sum(A1(:))       % percentage

P = 0.1199

A00 = rgb2gray(A0);
imshow(A0)

imshow(R)

[Chathurika Sandamali]

@darova Thank you very much for your answer but I want to find how many red points in the image.

[Image Analyst]

numberOfRedPixels = sum(R(:))
[~, numberOfRedBlobs] = bwlabel(R)

[Chathurika Sandamali]

I input the attached image called 'IMG_5058.jpg'. Using that I cannot get an image with red spots. (A0 = imread('image.png');). Can you help me to resolve that also.

[Image Analyst]

Correct. That particular image does not have red spots on it. darova's code was meant for your images that DO have red spots on them (meaning actually burned into and part of the image), like the one in your original post. Those spots were made by you calling plot() to put a red spot on the point. So to count the number of red spots with your code, you just need to count the number of times you call plot().