Image is displaying in different axes

Hi, I have a problem dispalying an image in a certain axes(axes4, btw). Everytime I click a certain option in the pop-up menu/list it always displays in axes5(additionally, it always displays on axes that are newly added or created, in my instance its axes5). Please do help Hoiw I do this.

Here is my code snippet.....

% --- Executes on selection change in popupmenu2.

function popupmenu2_Callback(hObject, eventdata, handles)

% hObject handle to popupmenu2 (see GCBO)

% eventdata reserved - to be defined in a future version of MATLAB

% handles structure with handles and user data (see GUIDATA)

% Hints: contents = cellstr(get(hObject,'String')) returns popupmenu2 contents as cell array

% contents{get(hObject,'Value')} returns selected item from popupmenu2

str = get(hObject, 'String');

val = get(hObject, 'Value');

% set current filter to the user-selected filter

switch str{val};

case 'RED'

a = imread('C:\Users\Vins\MATLAB_SAMPLE_Folder\Matlab\contrast.jpeg');

b = imagesc(a(:,:,1));

image(handles.axes4, b)

axis(handles.axes4, 'image', 'off');

case 'BLUE'

case 'GREEN'

end

Answer 1

[Deepak]

Hi @Veronica Alexandre,

We can display an image in a specific axes (axes4) based on a user selection from a popup menu by creating a GUI with an axes and a popup menu using MATLAB App Designer or GUIDE. The GUI should include options for different color channels (e.g., RED, BLUE, GREEN). In the callback function of popup menu, we read the image and extract the selected color channel. By setting "axes4" as the current axes using the "axes" function, we ensure that the "imagesc" function displays the image in the correct location, allowing dynamic updates based on user interaction.

Below is the sample MATLAB code to achieve the same:

function myImageDisplayApp
    % Create a figure
    hFig = figure('Name', 'Image Display App', 'NumberTitle', 'off', ...
                  'MenuBar', 'none', 'ToolBar', 'none', 'Position', [100, 100, 600, 400]);

    % Create axes4
    handles.axes4 = axes('Parent', hFig, 'Units', 'normalized', ...
                         'Position', [0.1, 0.3, 0.35, 0.6]);

    % Create popupmenu2
    handles.popupmenu2 = uicontrol('Style', 'popupmenu', ...
                                   'String', {'Select', 'RED', 'BLUE', 'GREEN'}, ...
                                   'Units', 'normalized', ...
                                   'Position', [0.5, 0.8, 0.3, 0.1], ...
                                   'Callback', @(hObject, eventdata) popupmenu2_Callback(hObject, eventdata, handles));

    % Callback function for popupmenu2
    function popupmenu2_Callback(hObject, ~, handles)
        str = get(hObject, 'String');
        val = get(hObject, 'Value');
        
        % Only proceed if a valid color is selected
        if val > 1
            % Load the image
            a = imread('C:\Users\dchangoi\Downloads\image1.JPG');
            
            % Select the color channel based on user selection
            switch str{val}
                case 'RED'
                    channel = a(:,:,1);
                case 'BLUE'
                    channel = a(:,:,3);
                case 'GREEN'
                    channel = a(:,:,2);
            end
            
            % Display the selected channel in axes4
            axes(handles.axes4); % Set the current axes to axes4
            imagesc(channel); % Display the selected color channel
            axis image off; % Adjust axis properties
        end
    end
end

Please find attached the documentation of functions used for reference:

uicontrol: www.mathworks.com/help/matlab/ref/uicontrol.html

axes: www.mathworks.com/help/matlab/ref/axes.html

imagesc: www.mathworks.com/help/matlab/ref/imagesc.html

I hope this assists in resolving the issue.