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

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);
% %             uiwait(helpdlg(message));
%             
%             Value = area2;
%             
%             
        app.EditField_4.Value = Value;
            
        end

        % Callback function
        function Image2Clicked(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

        % Value changed function: EditField_5
        function EditField_5ValueChanged(app, event)
            value = app.EditField_5.Value;
            
        end

        % Button pushed function: AverageDensityButton
        function AverageDensityButtonPushed(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;
            meanR = mean(redC(mask));
            meanG = mean(greenC(mask));
            meanB = mean(blueC(mask));
            
            
            % % 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)
            
            l = num2str(meanR);
            m = num2str(meanG);
            n = num2str(meanB);

            app.RedEditField.Value = l;
            app.GreenEditField.Value = m;
            app.BlueEditField.Value = n;
            
        end
    end

    % Component initialization
    methods (Access = private)

        % Create UIFigure and components
        function createComponents(app)

            % Create UIFigure and hide until all components are created
            app.UIFigure = uifigure('Visible', 'off');
            app.UIFigure.Position = [100 100 1282 808];
            app.UIFigure.Name = 'UI Figure';

            % Create MiddleEarPanel
            app.MiddleEarPanel = uipanel(app.UIFigure);
            app.MiddleEarPanel.TitlePosition = 'centertop';
            app.MiddleEarPanel.Title = 'Middle Ear';
            app.MiddleEarPanel.FontWeight = 'bold';
            app.MiddleEarPanel.Position = [11 18 1217 783];

            % Create ImagePanel
            app.ImagePanel = uipanel(app.MiddleEarPanel);
            app.ImagePanel.Title = 'Image Panel';
            app.ImagePanel.FontWeight = 'bold';
            app.ImagePanel.Position = [288 37 913 675];

            % Create Image_2
            app.Image_2 = uiimage(app.ImagePanel);
            app.Image_2.ImageClickedFcn = createCallbackFcn(app, @Image_2Clicked, true);
            app.Image_2.Position = [491 303 413 305];

            % Create Image
            app.Image = uiimage(app.ImagePanel);
            app.Image.ImageClickedFcn = createCallbackFcn(app, @AreaButtonPushed, true);
            app.Image.Position = [11 282 470 316];

            % Create Image2
            app.Image2 = uiimage(app.ImagePanel);
            app.Image2.Position = [70 14 623 239];

            % Create InfoPanel
            app.InfoPanel = uipanel(app.MiddleEarPanel);
            app.InfoPanel.Title = 'Info';
            app.InfoPanel.FontWeight = 'bold';
            app.InfoPanel.Position = [8 685 260 67];

            % Create FilenameEditFieldLabel
            app.FilenameEditFieldLabel = uilabel(app.InfoPanel);
            app.FilenameEditFieldLabel.HorizontalAlignment = 'right';
            app.FilenameEditFieldLabel.Position = [39 22 55 22];
            app.FilenameEditFieldLabel.Text = 'Filename';

            % Create FilenameEditField
            app.FilenameEditField = uieditfield(app.InfoPanel, 'text');
            app.FilenameEditField.ValueChangedFcn = createCallbackFcn(app, @OpenButtonPushed, true);
            app.FilenameEditField.ValueChangingFcn = createCallbackFcn(app, @AreaButtonPushed, true);
            app.FilenameEditField.Position = [109 22 100 22];

            % Create OptionPanel
            app.OptionPanel = uipanel(app.MiddleEarPanel);
            app.OptionPanel.Title = 'Option Panel';
            app.OptionPanel.FontWeight = 'bold';
            app.OptionPanel.Position = [9 582 260 88];

            % Create OpenButton
            app.OpenButton = uibutton(app.OptionPanel, 'push');
            app.OpenButton.ButtonPushedFcn = createCallbackFcn(app, @OpenButtonPushed, true);
            app.OpenButton.Position = [9 41 100 22];
            app.OpenButton.Text = 'Open ';

            % Create ProcessButton
            app.ProcessButton = uibutton(app.OptionPanel, 'push');
            app.ProcessButton.ButtonPushedFcn = createCallbackFcn(app, @ProcessButtonPushed, true);
            app.ProcessButton.Position = [119 41 100 22];
            app.ProcessButton.Text = 'Process';

            % Create IntensityProfileButton
            app.IntensityProfileButton = uibutton(app.MiddleEarPanel, 'push');
            app.IntensityProfileButton.ButtonPushedFcn = createCallbackFcn(app, @IntensityProfileButtonPushed, true);
            app.IntensityProfileButton.Position = [24 135 100 22];
            app.IntensityProfileButton.Text = 'Intensity Profile';

            % Create AreaButton
            app.AreaButton = uibutton(app.MiddleEarPanel, 'push');
            app.AreaButton.ButtonPushedFcn = createCallbackFcn(app, @AreaButtonPushed, true);
            app.AreaButton.Position = [16 530 100 22];
            app.AreaButton.Text = 'Area';

            % Create AverageDensityButton
            app.AverageDensityButton = uibutton(app.MiddleEarPanel, 'push');
            app.AverageDensityButton.ButtonPushedFcn = createCallbackFcn(app, @AverageDensityButtonPushed, true);
            app.AverageDensityButton.Position = [53 319 103 22];
            app.AverageDensityButton.Text = 'Average Density';

            % Create StandardDeviationButton
            app.StandardDeviationButton = uibutton(app.MiddleEarPanel, 'push');
            app.StandardDeviationButton.ButtonPushedFcn = createCallbackFcn(app, @StandardDeviationButtonPushed, true);
            app.StandardDeviationButton.Position = [62 494 118 22];
            app.StandardDeviationButton.Text = 'Standard Deviation';

            % Create Label_2
            app.Label_2 = uilabel(app.MiddleEarPanel);
            app.Label_2.HorizontalAlignment = 'right';
            app.Label_2.Position = [119 530 25 22];
            app.Label_2.Text = '';

            % Create EditField_5
            app.EditField_5 = uieditfield(app.MiddleEarPanel, 'text');
            app.EditField_5.ValueChangedFcn = createCallbackFcn(app, @EditField_5ValueChanged, true);
            app.EditField_5.Position = [159 530 100 22];

            % Create RedEditFieldLabel
            app.RedEditFieldLabel = uilabel(app.MiddleEarPanel);
            app.RedEditFieldLabel.HorizontalAlignment = 'right';
            app.RedEditFieldLabel.Position = [35 268 28 22];
            app.RedEditFieldLabel.Text = 'Red';

            % Create RedEditField
            app.RedEditField = uieditfield(app.MiddleEarPanel, 'text');
            app.RedEditField.Position = [78 268 100 22];

            % Create GreenEditFieldLabel
            app.GreenEditFieldLabel = uilabel(app.MiddleEarPanel);
            app.GreenEditFieldLabel.HorizontalAlignment = 'right';
            app.GreenEditFieldLabel.Position = [24 225 39 22];
            app.GreenEditFieldLabel.Text = 'Green';

            % Create GreenEditField
            app.GreenEditField = uieditfield(app.MiddleEarPanel, 'text');
            app.GreenEditField.Position = [78 225 100 22];

            % Create BlueEditFieldLabel
            app.BlueEditFieldLabel = uilabel(app.MiddleEarPanel);
            app.BlueEditFieldLabel.HorizontalAlignment = 'right';
            app.BlueEditFieldLabel.Position = [24 187 30 22];
            app.BlueEditFieldLabel.Text = 'Blue';

            % Create BlueEditField
            app.BlueEditField = uieditfield(app.MiddleEarPanel, 'text');
            app.BlueEditField.Position = [69 187 100 22];

            % Create RedStdEditFieldLabel
            app.RedStdEditFieldLabel = uilabel(app.MiddleEarPanel);
            app.RedStdEditFieldLabel.HorizontalAlignment = 'right';
            app.RedStdEditFieldLabel.Position = [45 457 46 22];
            app.RedStdEditFieldLabel.Text = 'RedStd';

            % Create RedStdEditField
            app.RedStdEditField = uieditfield(app.MiddleEarPanel, 'text');
            app.RedStdEditField.Position = [106 457 100 22];

            % Create GreenStdEditFieldLabel
            app.GreenStdEditFieldLabel = uilabel(app.MiddleEarPanel);
            app.GreenStdEditFieldLabel.HorizontalAlignment = 'right';
            app.GreenStdEditFieldLabel.Position = [45 415 57 22];
            app.GreenStdEditFieldLabel.Text = 'GreenStd';

            % Create GreenStdEditField
            app.GreenStdEditField = uieditfield(app.MiddleEarPanel, 'text');
            app.GreenStdEditField.Position = [117 415 100 22];

            % Create BlueStdEditFieldLabel
            app.BlueStdEditFieldLabel = uilabel(app.MiddleEarPanel);
            app.BlueStdEditFieldLabel.HorizontalAlignment = 'right';
            app.BlueStdEditFieldLabel.Position = [52 376 48 22];
            app.BlueStdEditFieldLabel.Text = 'BlueStd';

            % Create BlueStdEditField
            app.BlueStdEditField = uieditfield(app.MiddleEarPanel, 'text');
            app.BlueStdEditField.Position = [115 376 100 22];

            % Show the figure after all components are created
            app.UIFigure.Visible = 'on';
        end
    end

    % App creation and deletion
    methods (Access = public)

        % Construct app
        function app = Patient5

            % Create UIFigure and 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

[Adam Danz]

In your OPEN button callback function, why can't you just clear the field that shows the area value?

[Warid Islam]

Hi Adam,

I still get the same error message even I clear the field that shows the area value.

[Adam Danz]

Could you copy-paste the entire error message here (all of it)?

BTW, I haven't looked at your really long code. I can check it out as needed but it's way too long just to read through aimlessly.

[Warid Islam]

Hi Adam,

Please find the error message below:

Error using imread>parse_inputs (line 500)

The file name or URL argument must be a character vector or string scalar.

Error in imread (line 340)

[source, fmt_s, extraArgs, was_cached_fmt_used] = parse_inputs(cached_fmt, varargin{:});

Error in Patient5/AreaButtonPushed (line 140)

grayImage = imread(app.Image_2.ImageSource);

Error using matlab.ui.control.internal.controller.ComponentController/executeUserCallback (line 335)

Error while evaluating Button PrivateButtonPushedFcn.

I am copying the portion of the code below that calculates the area:

% 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
% 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)));

grayImage = imread(app.Image_2.ImageSource);

            % 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);

Please note that the error points to the line of the code below:

grayImage = imread(app.Image_2.ImageSource);

Please let me know what you think.

[Adam Danz]

The error you shared states "The file name or URL argument must be a character vector or string scalar."

Could you share what this variable contains?

app.Image.ImageSource

[Warid Islam]

Hi Adam,

The app.Image_2.ImageSource contains the cropped/masked image of the original image. Please take a look at the couple of attachments below. Intensity6.jpg is the original image and M2.jpg is the masked/cropped image. I want to find the area of the masked/cropped image. As I want to automate the entire process, i.e. I want to find the area of the masked/cropped image every time I click the AREA button in the GUI. The masking/cropping is done in the ProcessButtonPushed function( i.e. the process is performed when I click the PROCESS button in the GUI). I want to find the AREA of the resulting image that is generated after the PROCESS button is clicked. Previously, I needed to change the file name in the code every time I wanted to find AREA of a new image. However, as I want to find the area by clicking the AREA button in the GUI, so i tried to automate the process by storing the cropped/masked image in the app.Image_2.ImageSource function and then try to read the function. I think the problem lies in the code below although I am not sure.

grayImage = imread(app.Image_2.ImageSource);

Please note that the app.Image.ImageSource generates the original image when the OPEN button is clicked. The app.Image_2.ImageSource generates the cropped/masked image(after the PROCESS button is clicked) on which I want to find the area.

Thank you.

[Adam Danz]

"..so i tried to automate the process by storing the cropped/masked image in the app.Image_2.ImageSource function and then try to read the function. I think the problem lies in the code below although I am not sure. grayImage = imread(app.Image_2.ImageSource)"

Yes, this is where the problem is.

The first step is understanding the imread() function. Please take some time to read through the documentation and understand the inputs.

https://www.mathworks.com/help/matlab/ref/imread.html

The first input is a filename, not an image. If you're already reading in that file, can't you store the image data somewhere within the app?

[Warid Islam]

Hi Adam,

Thank you for the suggestion. That problem is solved. I have one more query. In my GUI(attached in the U.jpg image), when I click the INTENSITY PROFILE button, the resultant image is displayed on a new window, Whereas I want the image to be displayed on bottom image box of the image panel. Please find the code of the IntensityProfileButtonPushed(app, event) below: Any suggestion would be appreciated. Thank you.

 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

[Adam Danz]

Great!

I added an answer to summarize the first question and to answer your 2nd question.

Answer 1

[Adam Danz]

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.