MATLAB: Highlighting the contour of a specific region and its lowest end points.

highlighting two end pointsimage processingImage Processing ToolboxMATLABtracing contour

I have to plot the contour of an specific area of the attached 'InputImage.png' as shown by green countour in the attached 'sample…png'. I wanted to use bwtraceboundary() but I couldn't manage to determine the row and column coordinates of a pixel on the border. If I sort the biggest area, then is it possible to show the contour of that area?

Also, I have to highlight the two endpoints at the base as shown in the 'sample…png'. How can it be done?

Best Answer

I have solved the problem. The code is as below:

crownAndSecondaryDroplet=imread('inputImage.png');
%get the row number of the lowest white pixels
lowestRow = find(sum(crownAndSecondaryDroplet, 2)>0, 1, 'last');  % Bottom white row of the image
hp = impixelinfo(); %to check the output of the lowest row
%find the column numbers of the lowest row
colummsOfLowestRow= find(crownAndSecondaryDroplet(lowestRow,:)==1);
%find the x value for the leftmost and the rightmost pixels of the lowest row
lowestLeftXvalue = min(colummsOfLowestRow);
lowestRightXvalue = max(colummsOfLowestRow);
%get the boundary of the contour
boundary = bwtraceboundary(crownAndSecondaryDroplet,[lowestRow, lowestLeftXvalue],'N'); 
%display the image
figure, imshow(crownAndSecondaryDroplet, []);
title('Image with Rim Contour', 'FontSize', fontSize, 'Interpreter', 'None'); 
axis on;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
hold on;
%plot the contour and lowest end points
plot(boundary(:,2),boundary(:,1),'g','LineWidth',2);
plot(lowestLeftXvalue , lowestRow, 'r+', 'LineWidth', 3, 'MarkerSize', 20 ); 
plot(lowestRightXvalue , lowestRow, 'r+', 'LineWidth', 3, 'MarkerSize', 20 ); 
hold off;

Related Solutions

MATLAB: [HELP] Finding the lowest positioned pixel in the figure.

Guillaume's answer is good. I just wanted to add: don't do this:

image= [pos1];

All that does it to destroy the built-in function called image(), and nothing useful whatsoever in your code. It can be eliminated without any problem. Never use "image" as the name of a variable.

By the way, another possible method to find the lowest row is

lowestRow1 = find(sum(BW1, 2)>0, 1, 'last');  % Bottom dot in image #1
lowestRow2 = find(sum(BW2, 2)>0, 1, 'last');  % Bottom dot in image #2
output = [lowestRow1, lowestRow2];  % The output array you said you wanted.

Basically you're summing the image horizontally (across columns, which gives a mean vertical profile) and finding the last (lowest) row that has something in it. However I'm not sure why you want 343 and 423 when the lowest rows are 342 and 423 - why add 1 to the first image???

MATLAB: How to cut out an area that I’ve created a boundary to

Close. Here, try this:

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.
workspace;  % Make sure the workspace panel is showing.
format longg;
format compact;
fontSize = 20;
% Change the current folder to the folder of this m-file.
if(~isdeployed)
  cd(fileparts(which(mfilename)));
end
  
% Check that user has the Image Processing Toolbox installed.
hasIPT = license('test', 'image_toolbox');
if ~hasIPT
  % User does not have the toolbox installed.
  message = sprintf('Sorry, but you do not seem to have the Image Processing Toolbox.\nDo you want to try to continue anyway?');
  reply = questdlg(message, 'Toolbox missing', 'Yes', 'No', 'Yes');
  if strcmpi(reply, 'No')
    % User said No, so exit.
    return;
  end
end
% Read in a demo image.
folder = 'C:\Users\Student\Documents\Temporary';
baseFileName = '2z3nja1.jpg';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
  % File doesn't exist -- 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 in the search path folders.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
grayImage = rgb2gray(imread(fullFileName));
% Get the dimensions of the image.  
% numberOfColorBands should be = 1.
[rows columns numberOfColorBands] = size(grayImage);
% Display the original gray scale image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize);
% Enlarge figure to full screen.

set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Give a name to the title bar.

set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') 
% Let's compute and display the histogram.
[pixelCount grayLevels] = imhist(grayImage);
subplot(2, 2, 2); 
bar(pixelCount);
grid on;
title('Histogram of original image', 'FontSize', fontSize);
xlim([0 grayLevels(end)]); % Scale x axis manually.
% Find border and mask it off
binaryImage = grayImage == 255;
% Display the image.



subplot(2, 2, 3);
imshow(binaryImage, []);
title('Original Binary Image', 'FontSize', fontSize);
% Get just hte border pixels.
borderImage = logical(binaryImage - imclearborder(binaryImage));
% Move the outer edge in a little bit.
borderImage = imdilate(borderImage, true(7));
% Display the image.
subplot(2, 2, 4);
imshow(borderImage, []);
title('Border Pixels Image', 'FontSize', fontSize);
% Start a new figure.
figure;
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
% Give a name to the title bar.
set(gcf,'name','Demo by ImageAnalyst','numbertitle','off') 
% Erase border pixels.
grayImage(borderImage) = 0;
% Display the image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Masked Image', 'FontSize', fontSize);
% Threshold for dark pixels.
binaryImage3 = (grayImage > 0) & (grayImage < 125); % Threshold to isolate lung tissue
% Get the two largest blobs.
[labeledImage numberOfBlobs] = bwlabel(binaryImage3);
blobMeasurements = regionprops(labeledImage, 'Area');
allAreas = [blobMeasurements.Area];
[sortedAreas sortIndices] = sort(allAreas, 'descend');
% Get a list of the blobs that meet our criteria and we need to keep. 
keeperIndexes = [sortIndices(1), sortIndices(2)]; 
% Extract only those blobs that meet our criteria, and 
% eliminate those blobs that don't meet our criteria. 
% Note how we use ismember() to do this.
keeperBlobsImage = ismember(labeledImage, keeperIndexes); 
% Binarize and fill holes.
binaryImage3 = imfill(keeperBlobsImage>0, 'holes');
% Display the image.
subplot(2, 2, 2);
imshow(binaryImage3, []);
title('Two Largest Regions', 'FontSize', fontSize);
% Re-label with only the keeper blobs kept.
labeledImage = bwlabel(keeperBlobsImage, 8);     % Label each blob so we can make measurements of it
% Find outer boundaries and trace over image.
% bwboundaries() returns a cell array, where each cell contains the row/column coordinates for an object in the image.
% Plot the borders of two largest regions returned by bwboundaries.
subplot(2, 2, 3); 
imshow(grayImage, []);
title('Outlines, from bwboundaries()', 'FontSize', fontSize);
hold on;
boundaries = bwboundaries(binaryImage3);  
numberOfBoundaries = size(boundaries);
for k = 1 : numberOfBoundaries
  thisBoundary = boundaries{k};
  plot(thisBoundary(:,2), thisBoundary(:,1), 'g', 'LineWidth', 2);
end
hold off;
% Now let's extract out just the lungs.
maskedImage = zeros(rows, columns, 'uint8'); % Initialize.
maskedImage(binaryImage3) = grayImage(binaryImage3);
subplot(2, 2, 4); 
imshow(maskedImage, []);
title('Lungs Masked', 'FontSize', fontSize);

Best Answer

Related Solutions

MATLAB: [HELP] Finding the lowest positioned pixel in the figure.

MATLAB: How to cut out an area that I’ve created a boundary to

Related Question