MATLAB: How to find the area of an image and display the output in the GUI

Question

Hi,

I have created a GUI using the APP DESIGNER in Matlab. When I click the AREA button in the GUI, a value is displayed in the field beside the AREA button. However, problem arises when I click the OPEN button in the GUI. A new image is displayed in the Image Panel but the old value of the Area remains in the GUI. I have to manually change the filename in the code in order for the actual value to be displayed on the GUI. The other buttons work perfectly i.e. when I open a new file, all the previous values are replaced automatically with the new values. Only the AREA button is not working as desired. Please note that the AREA value would be that of the area of the Image on the right side of the Image Panel(app.Image_2.ImageSource or the image file that is generated after the ProcessButtonPushed function is performed.) Any suggestions would be very much appreciated.

classdef Patient5 < matlab.apps.AppBase

    % Properties that correspond to app components
    properties (Access = public)
        UIFigure                 matlab.ui.Figure
        MiddleEarPanel           matlab.ui.container.Panel
        ImagePanel               matlab.ui.container.Panel
        Image_2                  matlab.ui.control.Image
        Image                    matlab.ui.control.Image
        Image2                   matlab.ui.control.Image
        InfoPanel                matlab.ui.container.Panel
        FilenameEditFieldLabel   matlab.ui.control.Label
        FilenameEditField        matlab.ui.control.EditField
        OptionPanel              matlab.ui.container.Panel
        OpenButton               matlab.ui.control.Button
        ProcessButton            matlab.ui.control.Button
        IntensityProfileButton   matlab.ui.control.Button
        AreaButton               matlab.ui.control.Button
        AverageDensityButton     matlab.ui.control.Button
        StandardDeviationButton  matlab.ui.control.Button
        Label_2                  matlab.ui.control.Label
        EditField_5              matlab.ui.control.EditField
        RedEditFieldLabel        matlab.ui.control.Label
        RedEditField             matlab.ui.control.EditField
        GreenEditFieldLabel      matlab.ui.control.Label
        GreenEditField           matlab.ui.control.EditField
        BlueEditFieldLabel       matlab.ui.control.Label
        BlueEditField            matlab.ui.control.EditField
        RedStdEditFieldLabel     matlab.ui.control.Label
        RedStdEditField          matlab.ui.control.EditField
        GreenStdEditFieldLabel   matlab.ui.control.Label
        GreenStdEditField        matlab.ui.control.EditField
        BlueStdEditFieldLabel    matlab.ui.control.Label
        BlueStdEditField         matlab.ui.control.EditField
    end

    
    properties (Access = public)
        
        UIAxes    matlab.ui.control.UIAxes
        UIaxes    matlab.ui.control.UIAxes
    end
    
    
    
    
    
    
    
   
    

    % Callbacks that handle component events
    methods (Access = private)

        % Callback function: FilenameEditField, OpenButton
        function OpenButtonPushed(app, event)

           [filename,filepath] = uigetfile({'*.*;*.jpg;*.png;*.bmp;*.oct'}, 'Select File to Open');
           fullname = [filepath, filename];
           app.FilenameEditField.Value = "filename";
           
           app.Image.ImageSource = fullname;
           app.Image_2.ImageSource = "";
           app.EditField_5.Value = "";
            app.RedStdEditField.Value = "";
            app.GreenStdEditField.Value = "";
            app.BlueStdEditField.Value = "";
             app.RedEditField.Value = "";
            app.GreenEditField.Value = "";
            app.BlueEditField.Value = "";
            app.FilenameEditField.Value = "";
        end

        % Button pushed function: IntensityProfileButton
        function IntensityProfileButtonPushed(app, event)
            
            
            
            I = imread(app.Image.ImageSource);
           
            x=[size(I,2)/2 size(I,2)/2];
            y=[0 size(I,1)];
            c = improfile(I,x,y);
            figure
            subplot(2,1,1)
            imshow(I)
            hold on
            plot(x,y,'r')
            subplot(2,1,2)
            plot(c(:,1,1),'r')
            hold on
            plot(c(:,1,2),'g')
            plot(c(:,1,3),'b')
            
            
            
        end

        % Image clicked function: Image_2
        function Image_2Clicked(app, event)
            
          
            
           
        end

        % Button pushed function: ProcessButton
        function ProcessButtonPushed(app, event)
            img = imread(app.Image.ImageSource);
            
            % get red, green, blue channels


            redC = img(:,:,1);
            greenC = img(:,:,2);
            blueC = img(:,:,3);
            % mask where red channel is greater than blue channel and green channel greater than blue channel
            mask = redC > blueC & greenC > blueC;
            % overlay mask into original image
            finalimg = bsxfun(@times, img, cast(mask,class(img)));
       
            app.Image_2.ImageSource = finalimg;




        end

        % Button pushed function: StandardDeviationButton
        function StandardDeviationButtonPushed(app, event)
      img = imread(app.Image.ImageSource);

% get red, green, blue channels
redC = img(:,:,1);
greenC = img(:,:,2);
blueC = img(:,:,3);
% % mask where red channel is greater than blue channel and green channel greater than blue channel


 mask = redC > blueC & greenC > blueC;
 

D = std2(redC(mask));
E = std2(greenC(mask));
F = std2(blueC(mask));

            s = num2str(D);
            t = num2str(E);
            u = num2str(F);

            app.RedStdEditField.Value = s;
            app.GreenStdEditField.Value = t;
            app.BlueStdEditField.Value = u;



% % overlay mask into original image


%finalimg = bsxfun(@times, img, cast(mask,class(img)));
% %plotting
% figure
%  subplot(1,2,1)
%  imshow(img)
%  subplot(1,2,2)
%  imshow(finalimg)
     
        end

        % Callback function: AreaButton, FilenameEditField, Image
        function AreaButtonPushed(app, event)
         
%             


            %===============================================================================


            % Read in a standard MATLAB gray scale demo image.


%              folder = 'C:\Users\morteza\Downloads\Matlab\Matlab';
%              baseFileName = 'finalimg.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.
%                 	fullFileNameOnSearchPath = baseFileName; % No path this time.
%                 	if ~exist(fullFileNameOnSearchPath, '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
            M = imread(app.Image_2.ImageSource);
            grayImage = imread(M);
            % Get the dimensions of the image.
            % numberOfColorBands should be = 1.
            [rows, columns, numberOfColorBands] = size(grayImage);
            if numberOfColorBands > 1
               	% It's not really gray scale like we expected - it's color.
               	% Convert it to gray scale by taking only the green channel.
               	grayImage = grayImage(:, :, 2); % Take green channel.
            end
            % Display the original gray scale image.
%             subplot(2, 2, 1);


%             imshow(grayImage, []);


%             axis on;


%             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 he histogram.
%             [pixelCount, grayLevels] = imhist(grayImage);


%             subplot(2, 2, 2);


%             bar(grayLevels, pixelCount);


%             grid on;


%             title('Histogram of original image', 'FontSize', fontSize);


%             xlim([0 grayLevels(end)]); % Scale x axis manually.


            
            binaryImage = grayImage~= 40;
%             % Display the binary image.


%             subplot(2, 2, 3);


%             imshow(binaryImage, []);


%             axis on;
%             title('Binary Image', 'FontSize', fontSize);


%             
%             % Fill the binary image.


%             binaryImage = imfill(binaryImage, 'holes');


%             % Display the binary image.
%             subplot(2, 2, 4);


%             imshow(binaryImage, []);
%             axis on;
%             title('Filled Binary Image', 'FontSize', fontSize);


%             
            
            
            % Calculate the area using bwarea().
            area1 = bwarea(binaryImage);
            % Calculate the area in pixels using sum()
            area2 = sum(binaryImage(:));
%              message = sprintf('The area = %.1f, or %d\ndepending on how you want to calculate it', area1, area2);
%               uiwait(helpdlg(message));
            
             answer = num2str(area2);
%               Value = area2;
              app.EditField_5.Value = answer;
              
%             app.EditField_4ValueChanged.Value = num2str(Value);
         
              
        end

        % Callback function


        function EditField_4ValueChanged(app, event)
%         clc;    % Clear the command window.
%             close all;  % Close all figures (except those of imtool.)
%             imtool close all;  % Close all imtool figures if you have the Image Processing Toolbox.
%             clear;  % Erase all existing variables. Or clearvars if you want.
%             workspace;  % Make sure the workspace panel is showing.
%             format long g;
%             format compact;
%             fontSize = 22;
%             
%             % 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 standard MATLAB gray scale demo image.
%             folder = 'C:\Users\morteza\Downloads\Matlab\Matlab';
%             baseFileName = 'M1.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.
%                	fullFileNameOnSearchPath = baseFileName; % No path this time.
%                	if ~exist(fullFileNameOnSearchPath, '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 = imread(fullFileName);
%             % Get the dimensions of the image.
%             % numberOfColorBands should be = 1.
%             [rows, columns, numberOfColorBands] = size(grayImage);
%             if numberOfColorBands > 1
%                	% It's not really gray scale like we expected - it's color.
%                	% Convert it to gray scale by taking only the green channel.
%                	grayImage = grayImage(:, :, 2); % Take green channel.
%             end
%             % Display the original gray scale image.
%             subplot(2, 2, 1);
%             imshow(grayImage, []);
%             axis on;
%             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(grayLevels, pixelCount);
%             grid on;
%             title('Histogram of original image', 'FontSize', fontSize);
%             xlim([0 grayLevels(end)]); % Scale x axis manually.
%             
%             binaryImage = grayImage~= 40;
%             % Display the binary image.
%             subplot(2, 2, 3);
%             imshow(binaryImage, []);
%             axis on;
%             title('Binary Image', 'FontSize', fontSize);
%             
%             % Fill the binary image.
%             binaryImage = imfill(binaryImage, 'holes');
%             % Display the binary image.
%             subplot(2, 2, 4);
%             imshow(binaryImage, []);
%             axis on;
%             title('Filled Binary Image', 'FontSize', fontSize);
%             
%             
%             
%             % Calculate the area using bwarea().
%             area1 = bwarea(binaryImage);
%             % Calculate the area in pixels using sum()
%             area2 = sum(binaryImage(:));
% %             message = sprintf('The area = %.1f, or %d\ndepending on how you want to calculate it', area1, area2);

            
            

    

        

	
    

        
Best Answer
    

    

								

								
Answer to first question:
(Summarized from comments under the question)  The error is due to improper input to imread().  The expected input is a filename, not image data.  
Answer to second question:
The reason you're getting a new figure instead of plotting the image in you app axes is because you're directly creating the new figure in your code by calling figure().  Remove the line that creates a new figure and remove the lines that create new subplots. Instead, specify your UIAxes when you callmby specifying the parent property.  
 function IntensityProfileButtonPushed(app, event)
            
            
            
            I = imread(app.Image.ImageSource);
           
            x=[size(I,2)/2 size(I,2)/2];
            y=[0 size(I,1)];
            c = improfile(I,x,y);
            % figure                    REMOVE
            % subplot(2,1,1)            REMOVE
            imshow(I,'parent',app.UIAxes1)        % Use the correct axes handle

            hold(app.UIAxes1,'on')                % also specify the axes handle here




            plot(app.UIAxes1, x,y,'r')            % also specify the axes handle here
            %subplot(2,1,2)             REMOVE
            plot(app.UIAxes2, c(:,1,1),'r')       % Use the correct axes handle
            hold(app.UIAxes2,'on')                % also specify the axes handle here
            plot(app.UIAxes2,c(:,1,2),'g')        % also specify the axes handle here
            plot(app.UIAxes2,c(:,1,3),'b')        % also specify the axes handle here
             
            
        end
Lesson learned: always specify the axis handle when possible.  
						    
						
		
    
        

    

Related Solutions
MATLAB: How to display images in APP DESIGNER

								

								
If you want to display your image in a uiimage control, then simply assign the image to the ImageSource property of the control:
app.Image_2.ImageSource = someimage;
Note that the image must be RGB. If the image is greyscale, you need to convert it to RGB by repmat'ing the grey channel.
If you want to display your image in an uiaxes using imshow, then you need to specify the uiaxes as a parent in the call to imshow. You don't have a uiaxes in your app currently, so that option is not available to you:
imshow(someimage, 'Parent', app.someuiaxes)
Looking at your method IntensityProfileButtonPushed, you explicity create a figure:
            c = improfile(I,x,y);
            figure
so, it's no wonder that your image appear in that figure. The subsequent subplot and imshow all happen in that figure.
						    
						
MATLAB: Error: Missing multiplication operator, missing or unbalanced delimiters. To construct matrices, use brackets instead of parentheses.

								

								
Your updateimage function is not within a methods section.
						    
						
        
        

            
            
            
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Answer 1

Answer to first question:

(Summarized from comments under the question) The error is due to improper input to imread(). The expected input is a filename, not image data.

Answer to second question:

The reason you're getting a new figure instead of plotting the image in you app axes is because you're directly creating the new figure in your code by calling figure(). Remove the line that creates a new figure and remove the lines that create new subplots. Instead, specify your UIAxes when you callmby specifying the parent property.

 function IntensityProfileButtonPushed(app, event)
            
            
            
            I = imread(app.Image.ImageSource);
           
            x=[size(I,2)/2 size(I,2)/2];
            y=[0 size(I,1)];
            c = improfile(I,x,y);
            % figure                    REMOVE
            % subplot(2,1,1)            REMOVE
            imshow(I,'parent',app.UIAxes1)        % Use the correct axes handle

            hold(app.UIAxes1,'on')                % also specify the axes handle here




            plot(app.UIAxes1, x,y,'r')            % also specify the axes handle here
            %subplot(2,1,2)             REMOVE
            plot(app.UIAxes2, c(:,1,1),'r')       % Use the correct axes handle
            hold(app.UIAxes2,'on')                % also specify the axes handle here
            plot(app.UIAxes2,c(:,1,2),'g')        % also specify the axes handle here
            plot(app.UIAxes2,c(:,1,3),'b')        % also specify the axes handle here
             
            
        end

Lesson learned: always specify the axis handle when possible.