MATLAB: How to draw a free hand box on an image to select that region of interest

free hand box

hi,

I used this for free hand drawing in an irregular shape. But I need to draw a box to select a region.

 % Get the input free hand image
 figure, imshow(grayImage, []);
 axis on;
 title('Contour Region Required', 'FontSize', fontSize);
 set(gcf, 'Position', get(0,'Screensize')); % Maximize figure.
 message = sprintf('Left click and hold to begin drawing.\nRelease Mouse Button when Completed');
 uiwait(msgbox(message));
 hFH = imfreehand();
 % Create a binary image ("mask") from the ROI object.
 binaryImage = hFH.createMask();
 xy = hFH.getPosition;
 % Label the binary image and compute the centroid and center of mass.
 labeledImage = bwlabel(binaryImage);
 % Will keep only the part of the image that's inside the mask, zero outside mask.
 blackMaskedImage = grayImage;
 blackMaskedImage(~binaryImage) = 0;

Can you please suggest me free hand drawing a box.

Thanks…

Best Answer

To force it to a rectangle, use imrect which has the same api as imfreehand.

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MATLAB: Cropping DICOM image to exact size

OK, 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 = 25;
%===============================================================================

% Get the name of the image the user wants to use.
% Have user browse for a file, from a specified "starting folder."
% For convenience in browsing, set a starting folder from which to browse.
startingFolder = pwd;
if ~exist(startingFolder, 'dir')
  % If that folder doesn't exist, just start in the current folder.
  startingFolder = pwd;
end
% Get the name of the file that the user wants to use.
defaultFileName = fullfile(startingFolder, '*.*');
[baseFileName, folder] = uigetfile(defaultFileName, 'Select a file');
if baseFileName == 0
  % User clicked the Cancel button.
  return;
end
% Get the full filename, with path prepended.
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(1, 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 Mark Hayworth', 'NumberTitle', 'Off')
drawnow;
uiwait(msgbox('Drag out a 128x128 box'));
% Let user draw the box.
k = waitforbuttonpress;
point1 = get(gca,'CurrentPoint');    % button down detected
finalRect = rbbox;                   % return figure units
point2 = get(gca,'CurrentPoint');    % button up detected
point1 = point1(1,1:2);              % extract x and y
point2 = point2(1,1:2);
x1 = point1(1);
y1 = point1(2);
x2 = point2(1);
y2 = point2(2);
% Find the coordinates of the box.

xUserBox = [x1, x2, x2, x1, x1];
yUserBox = [y1, y1, y2, y2, y1];
% The box from rbbox() disappears after drawing.
% Redraw what they drew.
hold on
axis manual
plot(xUserBox, yUserBox, 'r-', 'LineWidth', 2); % Draw box.
% Now we need to get a 128x128 box centered at that location.
% Compute the center
xCenter = (x1 + x2)/2; % Get average.

yCenter = (y1 + y2)/2; % Get average.
plot(xCenter, yCenter, 'r+', 'MarkerSize', 30, 'LineWidth', 2); % Plot cross at center.
% Get box edges for a 128x128 box centered at the center of the box that they drew.
x1 = round(xCenter - 64)
y1 = round(yCenter - 64)
x2 = x1 + 127
y2 = y1 + 127
% Find the coordinates of the box.
xBox128 = [x1, x2, x2, x1, x1];
yBox128 = [y1, y1, y2, y2, y1];
% Draw the 128x128 box
plot(xBox128, yBox128, 'b-', 'LineWidth', 2);
% Display the image.
croppedImage = grayImage(y1:y2, x1:x2);
[rows, columns, numColors] = size(croppedImage) % Show values just to make sure.
subplot(1, 2, 2);
imshow(croppedImage, []);
axis on;
title('Cropped 128x128 Image', 'FontSize', fontSize, 'Interpreter', 'None');

MATLAB: How to crop automatically the interested region of an image

We have no idea what in that thing you want to segment out. So go here, find an algorithm, and code it up. If you still have questions, read this then come back.

Also see my Image Segmentation Tutorial where I "automatically" crop out things: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

Best Answer

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MATLAB: Cropping DICOM image to exact size

MATLAB: How to crop automatically the interested region of an image

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