how to track boundary of the red underlined image?
MATLAB: How to track boundary in matlab
image processing
Related Solutions
Mohsina, 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 short g;format compact;fontSize = 25;%===============================================================================
% Get the name of the image the user wants to use.
baseFileName = 'image1.png';% Get the full filename, with path prepended.
folder = []; % Determine where demo folder is (works with all versions).
fullFileName = fullfile(folder, baseFileName);%===============================================================================% Read in a demo image.
grayImage = imread(fullFileName);% Get the dimensions of the image.
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage)if numberOfColorChannels > 1 % It's not really gray scale like we expected - it's color.
% Use weighted sum of ALL channels to create a gray scale image.
grayImage = rgb2gray(grayImage); % ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
% which in a typical snapshot will be the least noisy channel.
% grayImage = grayImage(:, :, 2); % Take green channel.
end% Display the image.
subplot(2, 2, 1);imshow(grayImage, []);axis on;axis image;caption = sprintf('Original Gray Scale Image');title(caption, 'FontSize', fontSize, 'Interpreter', 'None');drawnow;hp = impixelinfo();% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0, 1, 1]);% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off')drawnow;% Create binary image of the black blobs from grayscale image.
binaryImage = grayImage == 0;% Get rid of the background.
binaryImage = imclearborder(binaryImage);% Display the image.subplot(2, 2, 2);imshow(binaryImage, []);axis on;axis image;title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');% Label the blobs
[labeledImage, numBlobs] = bwlabel(binaryImage);% Display the image.subplot(2, 2, 2);imshow(binaryImage, []);axis on;axis image;title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');% Let's assign each blob a different color to visually show the user the distinct blobs.
coloredLabels = label2rgb (labeledImage, 'hsv', 'k', 'shuffle'); % pseudo random color labels
% coloredLabels is an RGB image. We could have applied a colormap instead (but only with R2014b and later)
subplot(2, 2, 3);imshow(coloredLabels);axis on;axis image; % Make sure image is not artificially stretched because of screen's aspect ratio.
caption = sprintf('Pseudo colored labels, from label2rgb().');title(caption, 'FontSize', fontSize);drawnow;% Make measurements of bounding box.
props = regionprops(labeledImage, 'BoundingBox');% Display the image.subplot(2, 2, 4);imshow(binaryImage, []);axis on;axis image;title('Binary Image with Boxes', 'FontSize', fontSize, 'Interpreter', 'None');% Display the bounding boxes around them.
hold on;for k = 1 : numBlobs thisBoundingBox = props(k).BoundingBox rectangle('Position', thisBoundingBox, ... 'EdgeColor', 'c', 'LineWidth', 2);end
Here is some code which should work for this task:
Read in the image:
Image=imread('input.bmp'); figure imshow(Image)Get the red and green channel of the rgb-image:RedChannel=Image(:,:,1);GreenChannel=Image(:,:,2);Convert red areas to 1 and others to 0:
Image_BW = (RedChannel>200).* (GreenChannel<100);figure(1)clfimshow(Image_BW)Get the boundaries:
B=bwboundaries(Image_BW);Get and plot inner boundary
Bound=B{2};hold onplot(Bound(:,2),Bound(:,1),'g-')Get minimal and maximal x-position of roi
min_x=min(Bound(:,2));max_x=max(Bound(:,2));Image2=zeros(size(Image));%loop over columns intersecting roi
for i=min_x:max_x %get logical vector with 1s for roi-boundary-pixels in ith line
x=Bound(:,2)==i; %get minimal and maximal y-value of roi in ith column
min_y=min(Bound(x,1)); max_y=max(Bound(x,1)); %write ith column of roi to Image2
Image2(min_y:max_y,i,:)=Image(min_y:max_y,i,:);endPlot the result
figure(2)imshow(Image2);
Best Answer