I have been trying to draw a interactive rectangle in matlab appdesigner, over an existing image currently on the UIAxes. Is there anyway to allow user choose a region for processing

The image file is already loaded on the UIAxes. I need to create small regions in the image so I can extract and process from.

classdef Program02 

    if true
      % code
    end< matlab.apps.AppBase

      % Properties that correspond to app components
      properties (Access = public)
          UIFigure                       matlab.ui.Figure
          UIAxes                         matlab.ui.control.UIAxes
          Load2ImagesButton              matlab.ui.control.Button
          ToggleImagesSwitchLabel        matlab.ui.control.Label
          ToggleImagesSwitch             matlab.ui.control.ToggleSwitch
          UITable                        matlab.ui.control.Table
          CorrelationWindowsizeDropDownLabel  matlab.ui.control.Label
          CorrelationWindowsizeDropDown  matlab.ui.control.DropDown
      end

      properties (Access = private)
          _ _imgObj; % Object for loading and displaying images
          A;B; test;   % Objects used in switching between 2 images__
      end

      methods (Access = private)

          % Button pushed function: Load2ImagesButton
          function Load2ImagesButtonPushed(app, event)
              [File,Path] = uigetfile({'*.jpg;*.png;*.bmp;*.tif';'*.*'},...
                  'Select Two Images to Process (hold ctrl + shift and click on 2 images)',...
                  'MultiSelect', 'on');   %%opens user interface for selecting

        %%two image files
              if (length(File))~=2
                  text = ['Sorry, Please select 2 images,'...
                      '\nby holding Ctrl and Click on 2 images'...
                      '\n You must only select 2 images'...
                      '\n Continue or Exit?'];
                  message = sprintf(text);
                  reply = questdlg(message, 'Select 2 images',...
                      'Continue', 'Exit', 'Continue');
                  if strcmpi(reply, 'Exit')
                      % User said No, so exit.
                      return;
                  else
                      [File,Path] = uigetfile({'*.jpg;*.png;*.bmp;*.tif';'*.*'},...
                  'Select Two Images to Process (hold ctrl + shift and click on 2 images)',...
                  'MultiSelect', 'on');   % opens user interface for selecting
              % two image files
                  end

              end
              app.A = strcat(Path,File{1}); %%creates file directory for first  for first image selected
              app.B = strcat(Path,File{2}); %%creates file directory and object for first for second image selected

              if ~isempty(app.A)  %%check if there is any selected image files
                  imshow(app.A,'Parent',app.UIAxes); %%displays first selected image
                  l=imfinfo(app.A); % gets the information of selected image
                   %and presents it in structure format
                  d = {'Image Height',l.Height;'Image Width',l.Width;...
                      'Image size in bytes',l.FileSize;...
                      'Image Format', l.Format;...
                      'Image Bit depth', l.BitDepth}; % cell matrix with required
                  % image info
                  app.UITable.Data=d; %%display required info on UI table
              else
                  % displays on home screen error message if cancel button is selected
                  disp('no file selcted,Please select Images to Process');
              end
          end

          % Value changed function: ToggleImagesSwitch
          function ToggleImagesSwitchValueChanged(app, event)
              value = app.ToggleImagesSwitch.Value;
              if (strcmpi(value,'Image 2') ) %%compares if the switch is on or off
                  imshow(app.A,'Parent',app.UIAxes); %%shows 1st image if switch off
                  l=imfinfo(app.A);   %%collect 1st image info
                  d = {'Image Height',l.Height;'Image Width',l.Width;...
                      'Image size in bytes',l.FileSize;...
                      'Image Format', l.Format;...
                      'Image Bit depth', l.BitDepth}; %%cell matrix with required
                  %%image info
                  app.UITable.Data=d;%%display required info on UI table

              else
                  imshow(app.B,'Parent',app.UIAxes);%%shows 2nd image if switch on
                  k=imfinfo(app.B);  %%collects 2nd image info
                  e = {'Image Height',k.Height;'Image Width',k.Width;...
                      'Image size in bytes',k.FileSize;...
                      'Image Format', k.Format;...
                      'Image Bit depth', k.BitDepth};%%cell matrix with required
                  %%image info
                  app.UITable.Data=e;%%display required info on UI table

              end
          end

          % Value changed function: CorrelationWindowsizeDropDown
          function CorrelationWindowsizeDropDownValueChanged(app, event)
              value = app.CorrelationWindowsizeDropDown.Value;
              if (strcmpi(value,'16X16') ) % for each drop down window

                  h = drawrectangle('Parent',app.UIAxes,...
                      'Position',[10,10,100,100],'EdgeColor','b');
              end

          end
      end

      % App initialization and construction
      methods (Access = private)

          % Create UIFigure and components
          function createComponents(app)

              % Create UIFigure
              app.UIFigure = uifigure;
              app.UIFigure.Position = [100 100 746 527];
              app.UIFigure.Name = 'UI Figure';

              % Create UIAxes
              app.UIAxes = uiaxes(app.UIFigure);
              title(app.UIAxes, 'Images')
              app.UIAxes.Position = [316 211 309 292];

              % Create Load2ImagesButton
              app.Load2ImagesButton = uibutton(app.UIFigure, 'push');
              app.Load2ImagesButton.ButtonPushedFcn = createCallbackFcn(app, @Load2ImagesButtonPushed, true);
              app.Load2ImagesButton.Position = [50 402 126 37];
              app.Load2ImagesButton.Text = 'Load 2 Images';

              % Create ToggleImagesSwitchLabel
              app.ToggleImagesSwitchLabel = uilabel(app.UIFigure);
              app.ToggleImagesSwitchLabel.HorizontalAlignment = 'center';
              app.ToggleImagesSwitchLabel.Position = [59 61 80 22];
              app.ToggleImagesSwitchLabel.Text = 'ToggleImages';

              % Create ToggleImagesSwitch
              app.ToggleImagesSwitch = uiswitch(app.UIFigure, 'toggle');
              app.ToggleImagesSwitch.Items = {'Image 1', 'Image 2'};
              app.ToggleImagesSwitch.ValueChangedFcn = createCallbackFcn(app, @ToggleImagesSwitchValueChanged, true);
              app.ToggleImagesSwitch.Position = [79 114 38 86];
              app.ToggleImagesSwitch.Value = 'Image 2';

              % Create UITable
              app.UITable = uitable(app.UIFigure);
              app.UITable.ColumnName = {'Column 1'; 'Column 2'};
              app.UITable.RowName = {};
              app.UITable.Position = [259 30 302 170];

              % Create CorrelationWindowsizeDropDownLabel
              app.CorrelationWindowsizeDropDownLabel = uilabel(app.UIFigure);
              app.CorrelationWindowsizeDropDownLabel.HorizontalAlignment = 'right';
              app.CorrelationWindowsizeDropDownLabel.Position = [19 279 135 22];
              app.CorrelationWindowsizeDropDownLabel.Text = 'Correlation Window size';

              % Create CorrelationWindowsizeDropDown
              app.CorrelationWindowsizeDropDown = uidropdown(app.UIFigure);
              app.CorrelationWindowsizeDropDown.Items = {'8X8', '16X16', '32X32', '64X64', '128X128', '256X256'};
              app.CorrelationWindowsizeDropDown.ValueChangedFcn = createCallbackFcn(app, @CorrelationWindowsizeDropDownValueChanged, true);
              app.CorrelationWindowsizeDropDown.Position = [170 279 100 22];
              app.CorrelationWindowsizeDropDown.Value = '8X8';
          end
      end

      methods (Access = public)

          % Construct app
          function app = MECH6505_Program02_Omeziri_Chukwuibuikem

              % Create and configure components
              createComponents(app)

              % Register the app with App Designer
              registerApp(app, app.UIFigure)

              if nargout == 0
                  clear app
              end
          end

          % Code that executes before app deletion
          function delete(app)

              % Delete UIFigure when app is deleted
              delete(app.UIFigure)
          end
      end
  end

Answer 1

[Image Analyst]

You can use either imrect() in the Image Processing Toolbox, or rbbox() in base MATLAB.

[Biraj Khanal]

rbbox() opens a new figure instead of letting the user draw in the same axes. How do we control that? The idea is to let the user draw in the axes in which the plot is, right?

[Image Analyst]

@Biraj Khanal don't use rbbox. It's deprecated. Use drawrectangle instead. Demos attached.

[Biraj Khanal]

Thank you! When you use drawrectangle, how do you clear / delete the previous rectangle user drew when a new one is drawn ? In your example drawrectangle_demo, if you click redraw, the previous rectangle remains there. How do we fix that?

[Image Analyst]

You can call delete(hRect) if you want to clear the old one, like this:

% Demo to show how drawrectangle can be used to draw a rectangular box on the image.
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 = 20;
rgbImage = imread('peppers.png');
hFig = figure;
imshow(rgbImage);
hFig.WindowState = 'maximized';
% Ask user to draw rectangle.
button = 'Redraw';
while contains(button, 'Redraw', 'IgnoreCase',true)
    uiwait(helpdlg('Draw a box'));
    % User draws a box.  It exits as soon as they lift the mouse.
    hBox = drawrectangle('Color', 'r');
    
    % Get the coordinates in the form [xLeft, yTop, width, height].
    roiPosition = hBox.Position;
    % Delete the ROI object.
    delete(hBox);
    % and replace it with a rectangle in the graphical overlay.
    hold on;
    hRect = rectangle('Position', roiPosition, 'EdgeColor', 'r', 'LineWidth', 2);
    % Ask user if the rectangle is acceptable.
    message = sprintf('Is this good?');
    button = questdlg(message, message, 'Accept', 'Redraw', 'Reject and Quit', 'Accept');
    if contains(button, 'Quit','IgnoreCase',true)
        delete(hRect); % Delete the box from the overlay.
        roiPosition = [];
        break;
    elseif contains(button, 'Redraw','IgnoreCase',true)
        % OPTIONAL If you want to delete the prior one before drawing the next one.
        delete(hRect);
    elseif contains(button, 'Accept','IgnoreCase',true)
        break;
    end
end
% If you want to delete the rectangle from the overlay, do this:
delete(hRect); % Delete the box from the overlay.
% Close down figure.
close(hFig);

[Biraj Khanal]

Yes, that works. Thanks!!

I started another question for the same topic. I am also trying to do this without the image processsing toolbox to learn the keypress and windowbuttonpress functions in appdesigner. Not sure if linking to another question is allowed here, but could you please help?

https://de.mathworks.com/matlabcentral/answers/1728335-interactive-rectangle-on-uiaxes-for-user-to-choose-a-region

Answer 2

[Rami Babayew]

@Image Analyst hi, thank you for your example. its works great in app designer, but when im trying to work on stand alone mode (execute file) it wont opening the figure for selecting the box region. i dont understand why. do you have a clue?

[Image Analyst]

No. It should work. Does it just go silent? Does it put any warnings in the console window when it tries to open the figure? I do it all the time in compiled programs and it works fine.

[Rami Babayew]

its not silent, theres a sound of error while trying to push the checkbox which opens the figure to select the box. which console window? in the matlab infrastructure itself or there are a dedicated window for debugging a standalone apps?

is ther a event log for stand alone apps?

thx!

[Image Analyst]

when you compile the app with mcc there is a black console/"DOS" window that opens along side your GUI. It should be there unless you compiled with the "-e" option. What does it say in that window when it "dings"?

[Rami Babayew]

ok i found it. now i have the console, il try to debug the error. much appriciation!

[Rami Babayew]

@Image Analyst

the error in the console is :

Error using matlab.ui.control.internal.controller.ComponentController/executeUserCallback

after getting this error i have tried to add try catch and the app showed me pop up msg saying: 'unrecognised function or variable "workspace" '

i have no clue what is wrong

[Image Analyst]

workspace is a function that can only be called from within the MATLAB integrated development environment, as are all other panels that you can display in MATLAB, as well as any of the "Apps" shown on the Apps tab of the tool ribbon. The workspace panel is meant for helping you debug your code and is not meant to be shown in compiled programs. If you want to display the values of some variables, you'll have to use fprint() to print them out to the command window, or else put some place on your GUI where you can show them, like a table or edit fields or static text labels.

[Rami Babayew]

thank you! its workd fine now :-) have a great weekend!