MATLAB: How can i count the number of circles with random centers and fixed diameters.

I want to get a plot of size of circles(pixels) vs. their numbers. Example 10 of 20 pixels, 15 of 10 pixels size etc.. the background should be contrast of intensity of the circles..

Best Answer

See my Image Segmentation Tutorial. It determines the size distribution of circles (coins). http://www.mathworks.com/matlabcentral/fileexchange/25157-image-segmentation-tutorial-blobsdemo You just need to call bar() to display them.

You might also try imfindcircles() in the Image Processing Toolbox, or see Brett's demo: http://www.mathworks.com/matlabcentral/fileexchange/34365-findcirclesgui

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables.
workspace;  % Make sure the workspace panel is showing.
format longg;
format compact;
fontSize = 20;
% Get centroid via bwboundaries and incorrect method.
rgbImage = imread('D:\Temporary stuff\welcome-green-circles-layout.jpg');
subplot(2, 2, 1);
imshow(rgbImage);
title('Original Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Get centroid correctly via regionprops
binaryImage = rgbImage(:,:,1) < 200;
subplot(2, 2, 2);
imshow(binaryImage);
title('Binary Image with Centroids', 'FontSize', fontSize);
hold on;
measurements = regionprops(binaryImage, 'Centroid', 'Area');
numberOfCircles = length(measurements);
allAreas = [measurements.Area]
for k = 1 : numberOfCircles
  centroid = [measurements(k).Centroid];
  xCenter = centroid(1);
  yCenter = centroid(2);
  plot(xCenter, yCenter, 'b+');
end
[counts values] = hist(allAreas);
subplot(2, 2, 3);
bar(values, counts);
grid on;
title('Histogram of Areas (the size distribution)', 'FontSize', fontSize);
message = sprintf('The number of circles is %d', numberOfCircles);
msgbox(message);

Related Solutions

MATLAB: Crop dark area and display the face only

Convert to grayscale and then threshold and find the bounding box

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures.
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
% Read in the color image.
folder = pwd;
baseFileName = 'm2.bmp';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
if ~exist(fullFileName, 'file')
  % Didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
rgbImage = imread(fullFileName);
% Get the dimensions of the image.  numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(rgbImage);
% Display the original color image.
subplot(2, 3, 1);
imshow(rgbImage, []);
axis on;
title('Original Color Image', 'FontSize', fontSize);
drawnow;
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Histogram the red channel, but there is a huge spike at 255 so let's not count those.
subplot(2, 3, 2);
grayImage = rgb2gray(rgbImage);
imshow(grayImage, []);
title('Gray Scale version', 'FontSize', fontSize);
subplot(2, 3, 3);
histogram(grayImage(grayImage<255))
grid on;
title('Histogram of Gray Scale Image', 'FontSize', fontSize);
someThresholdValue = 150;
binaryImage = grayImage > someThresholdValue;
% Take largest blob
binaryImage = bwareafilt(binaryImage, 1);
subplot(2, 3, 4);
imshow(binaryImage);
grid on;
title('Binary Image', 'FontSize', fontSize);
% Label the binary image.
labeledImage = bwlabel(binaryImage);
props = regionprops(labeledImage, 'BoundingBox');
bbox = props.BoundingBox
croppedImageRGB = imcrop(rgbImage, bbox);
subplot(2, 3, 5);
imshow(croppedImageRGB);
grid on;
title('Cropped RGB Image', 'FontSize', fontSize);
% Gray scale version of cropped image
croppedImageGray = imcrop(grayImage, bbox);
subplot(2, 3, 6);
imshow(croppedImageGray);
grid on;
title('Cropped Gray Scale Image', 'FontSize', fontSize);

MATLAB: How to detect hand from body in pic

I have to detect hand from an image. First when I tried your code that is given in link below: https://www.mathworks.com/matlabcentral/answers/112917-how-to-detect-hand It was detecting my complete image as an one object, so I use skin segmentation then it detect my hand with an arm area as shown in given figure. Can you please tell me how can I detect hand from an arm.

folder=('C:\Users\Tayaba Abro\Desktop'); baseFileName=('hand.jpg'); fullFileName=fullfile(folder,baseFileName); format long g; format compact; fontSize = 20;

%IMAGE SEGMENTATION
img=imread(fullFileName);
img=rgb2ycbcr(img);
for i=1:size(img,1)
    for j= 1:size(img,2)
        cb = img(i,j,2);
        cr = img(i,j,3);
        if(~(cr > 132 && cr < 173 && cb > 76 && cb < 126))
            img(i,j,1)=235;
            img(i,j,2)=128;
            img(i,j,3)=128;
        end
    end
end
img=ycbcr2rgb(img);
subplot(2,2,1);
image1=imshow(img);
axis on;
title('Skin Segmentation', 'FontSize', fontSize);
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
%SEGMENTED IMAGE TO GRAYIMAGE
grayImage=rgb2gray(img);
subplot(2,2,2);
image2=imshow(grayImage);
axis on;
title('Original Grayscale Image', 'FontSize', fontSize);
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
%GRAY TO BINARY IMAGE
binaryImage = grayImage < 245;
subplot(2, 2, 3);
axis on;
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize);
% Label the image 
labeledImage = bwlabel(binaryImage);  % labeling is the process of identifying the connected components in an image and assigning each one a unique label, like this:
measurements = regionprops(labeledImage, 'BoundingBox', 'Area');
for k = 1 : length(measurements)
  thisBB = measurements(k).BoundingBox;
  rectangle('Position', [thisBB(1),thisBB(2),thisBB(3),thisBB(4)],...
  'EdgeColor','r','LineWidth',2 )
end
% Let's extract the second biggest blob - that will be the hand.
allAreas = [measurements.Area];
[sortedAreas, sortingIndexes] = sort(allAreas, 'descend');
handIndex = sortingIndexes(2); % The hand is the second biggest, face is biggest.
% Use ismember() to extact the hand from the labeled image.
 handImage = ismember(labeledImage, handIndex);
% Now binarize
handImage = handImage > 0;
% Display the image.
subplot(2, 2, 4);
imshow(handImage, []);
title('Hand Image', 'FontSize', fontSize);

Best Answer

Related Solutions

MATLAB: Crop dark area and display the face only

MATLAB: How to detect hand from body in pic

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