imrect function how I can show the image ?

Question

Khaled Al-Faleh 2017-4-14

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/335423-imrect-function-how-i-can-show-the-image

评论： Image Analyst 2017-4-15

Hi guys, I want to show the position that I choosed by using imrect for example see the code ..

I = imread('---.png');
imshow(I);
h = imrect;
imshow(h);

here I want to show the h How I can do it ??

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Khaled Al-Faleh 2017-4-14

I cropped the image by rectangular box using imrect so I want to show that cropped ..

Khaled Al-Faleh 2017-4-14

11.jpg

let say that I have this image I i used imrect to select what I want from the image so I need to show that selection ... is it clear ?

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Answer 1

Image Analyst 2017-4-14

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/335423-imrect-function-how-i-can-show-the-image#answer_263074

在 MATLAB Online 中打开

white_balancing.m

See this snippet from the attached demo.

% Have user specify the area they want to define as neutral colored (white  or gray).
promptMessage = sprintf('Drag out a box over the ROI you want to be neutral colored.\nDouble-click inside of it to finish it.');
titleBarCaption = 'Continue?';
button = questdlg(promptMessage, titleBarCaption, 'Draw', 'Cancel', 'Draw');
if strcmpi(button, 'Cancel')
  return;
end
hBox = imrect;
roiPosition = wait(hBox);  % Wait for user to double-click
roiPosition % Display in command window.
% Get box coordinates so we can crop a portion out of the full sized image.
xCoords = [roiPosition(1), roiPosition(1)+roiPosition(3), roiPosition(1)+roiPosition(3), roiPosition(1), roiPosition(1)];
yCoords = [roiPosition(2), roiPosition(2), roiPosition(2)+roiPosition(4), roiPosition(2)+roiPosition(4), roiPosition(2)];
croppingRectangle = roiPosition;
% Display (shrink) the original color image in the upper left.
subplot(2, 4, 1);
imshow(rgbImage);
title('Original Color Image', 'FontSize', fontSize);
% Crop out the ROI.
whitePortion = imcrop(rgbImage, croppingRectangle);
subplot(2, 4, 5);
imshow(whitePortion);
caption = sprintf('ROI.\nWe will Define this to be "White"');
title(caption, 'FontSize', fontSize);

Once you have croppingRectangle you can put it into the overlay above the image using rectangle(). Or you could use xCoords and yCoords and the plot() function to plot the box over the image.

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Image Analyst 2017-4-15

在 MATLAB Online 中打开

Yes I understand. Perhaps my demo was too much so I scaled it back to just the essential stuff, or at least less than there was before. Here it is - hope you can follow it now:

% Asks the user to draw a box and displays it on the image.
% Crops out the part of the image within the box to a new image.
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 long g;
format compact;
fontSize = 15;
% Read in a standard MATLAB color demo image.
baseFileName = 'peppers.png';
folder = fileparts(which('peppers.png')); % Determine where demo folder is (works with all versions).
% 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, colorMap] = imread(fullFileName);
% Get the dimensions of the image.  numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(rgbImage);
% If it's an indexed image (such as Kids),  turn it into an rgbImage;
if numberOfColorBands == 1
  rgbImage = ind2rgb(rgbImage, colorMap); % Will be in the 0-1 range.
  rgbImage = uint8(255*rgbImage); % Convert to the 0-255 range.
end
% Display the original color image full screen
imshow(rgbImage);
axis on;
title('Double-click inside box to finish box', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition', [0 0 1 1]);
% Have user specify the area they want to define as neutral colored (white  or gray).
promptMessage = sprintf('Drag out a box over the ROI you want.\nDouble-click inside of it to finish it.');
titleBarCaption = 'Continue?';
button = questdlg(promptMessage, titleBarCaption, 'Draw', 'Cancel', 'Draw');
if strcmpi(button, 'Cancel')
  return;
end
hBox = imrect;
roiPosition = wait(hBox);  % Wait for user to double-click
roiPosition % Display in command window.
% Get box coordinates so we can crop a portion out of the full sized image.
xCoords = [roiPosition(1), roiPosition(1)+roiPosition(3), roiPosition(1)+roiPosition(3), roiPosition(1), roiPosition(1)];
yCoords = [roiPosition(2), roiPosition(2), roiPosition(2)+roiPosition(4), roiPosition(2)+roiPosition(4), roiPosition(2)];
croppingRectangle = roiPosition;
% Display (shrink) the original color image in the top half.
subplot(2, 1, 1);
imshow(rgbImage);
title('Original Color Image', 'FontSize', fontSize);
% Plot the box again so we can see it.
hold on;
plot(xCoords, yCoords, 'r-', 'LineWidth', 3);
rectangle('Position', croppingRectangle);
% Crop out the ROI.
croppedPortion = imcrop(rgbImage, croppingRectangle);
subplot(2, 1, 2);
imshow(croppedPortion);
caption = sprintf('ROI you drew');
title(caption, 'FontSize', fontSize);
message = sprintf('Done with the demo.');
uiwait(helpdlg(message));

Khaled Al-Faleh 2017-4-15

how we can do it sir ?

Image Analyst 2017-4-15

在 MATLAB Online 中打开

You can use the function rbbox() instead of imrect():

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);
p1 = min(point1,point2);             % calculate locations
offset = abs(point1-point2);         % and dimensions
% Find the coordinates of the box.
xCoords = [p1(1) p1(1)+offset(1) p1(1)+offset(1) p1(1) p1(1)];
yCoords = [p1(2) p1(2) p1(2)+offset(2) p1(2)+offset(2) p1(2)];
x1 = round(xCoords(1));
x2 = round(xCoords(2));
y1 = round(yCoords(5));
y2 = round(yCoords(3));
width = x2-x1;
height = y2-y1;
% The box from rbbox() disappears after drawing, so redraw the box over the image.
hold on
axis manual
plot(xCoords, yCoords, 'b-'); % redraw in dataspace units