app not finding image files on some installation (Matlab 2019 problem ?)

I developped a visual App for Matlab but the behaviour is different based on different computer.

Here is my code that is working on my computer and on one of my colleague (both Windows 10).

I also join an archive with the images and the script.

classdef roiApp_example < matlab.apps.AppBase

    % Properties that correspond to app components
    properties (Access = public)
        UIFigure             matlab.ui.Figure
        ImageAxes            matlab.ui.control.UIAxes
        LoadImageButton      matlab.ui.control.Button
        projectionDropdown   matlab.ui.control.DropDown
        roiBackgroundButton  matlab.ui.control.Button
    end
    
    methods (Access = private)
        % Create UIFigure and components
        function createComponents(app)
            disp(pwd)

           
            addpath([pwd,'/icons/']);
%             addpath(genpath([pwd,'/icons/']));
            app.UIFigure = uifigure('Visible', 'off');
            app.UIFigure.AutoResizeChildren = 'off';
            app.UIFigure.Position = [100 100 1500 900];
            app.UIFigure.Name = 'ROI drawer App';
            app.UIFigure.Resize = 'off';
       
            % Create ImageAxes
            app.ImageAxes = uiaxes(app.UIFigure);
            app.ImageAxes.XTick = [];
            app.ImageAxes.XTickLabel = {'[ ]'};
            app.ImageAxes.YTick = [];
            app.ImageAxes.Position = [1 181 0.45*app.UIFigure.Position(3) 0.45*app.UIFigure.Position(3)];
            app.ImageAxes.Interactions = [zoomInteraction, regionZoomInteraction];

            % Create LoadButton
            app.LoadImageButton = uibutton(app.UIFigure, 'push');
            app.LoadImageButton.ButtonPushedFcn = createCallbackFcn(app, @LoadImage, true);
            app.LoadImageButton.Position = [20 10 225 22];
            app.LoadImageButton.Text = 'Load Tiff stack';
           
            % Create projectionDropdown
            app.projectionDropdown = uidropdown(app.UIFigure);
            app.projectionDropdown.ValueChangedFcn = createCallbackFcn(app, @ChangeProjection, true);
            app.projectionDropdown.Position = [250 10 225 22];
            app.projectionDropdown.Items = {'Min', 'Mean', 'Max'};
            app.projectionDropdown.Value = 'Max';
            
             % Create Button
            app.roiBackgroundButton = uibutton(app.UIFigure, 'push');
            app.roiBackgroundButton.Position = [630 60 75 75];
            app.roiBackgroundButton.Text = '';
            app.roiBackgroundButton.Tooltip = 'Background';
            app.roiBackgroundButton.Icon = imread('icons/background.png');
            app.roiBackgroundButton.BackgroundColor = '#e6e6e6';
            app.roiBackgroundButton.ButtonPushedFcn = createCallbackFcn(app, @add_background_ROI, true);
            
            app.UIFigure.Visible = 'on';
        end
    end

    methods (Access = public)
        function startupFcn(app)
            % Configure image axes
            app.ImageAxes.Visible = 'off';
            app.ImageAxes.Colormap = gray(256);
            axis(app.ImageAxes, 'image');
        end

        % Construct app
        function app = roiApp_example

            % Create UIFigure and components
            createComponents(app)

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

            % Execute the startup function
            runStartupFcn(app, @startupFcn)

            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

On two others computers I receive this error message

Error using matlab.ui.control.internal.model.mixin.IconableComponent/set.Icon (line 54)
You have specified a file that cannot be found or is not an image.
Specify a file name that is on the MATLAB path, or use a full or relative path.

Error in roiApp_example/createComponents (line 52)
            app.roiBackgroundButton.Icon = imread('icons/background.png');

Error in roiApp_example (line 72)
            createComponents(app)

I added this folder manually in path and also in the code.

imread('icons/background.png')

is working and find the img.

The two working computers are on 2020a, a faulty one is on 2019b but it looks strange if this is the cause of the problem

Answer 1

[Aymeric Ferreira]

Updating installation Matlab from R2019 to R2021 solved the issue so it was definitively an error depending on Matlab option.

I decided to handle it with a message warning

matlabVersion = version('-release');
matlabVersion = str2num(matlabVersion(1:4));
if matlabVersion < 2020
    warning('Matlab version should be 2020 or higher. This version will not show icons')
end

And then a condition to show text only instead of icon on older Matlab versions

app.roiBackgroundButton.Text = '';
if matlabVersion < 2020
    app.roiBackgroundButton.Text = {'Background', 'ROI'};
else
    app.roiBackgroundButton.Icon = imread('icons/background.png');
end