Error while evaluating UIControl Callback.

Hi Professors and Fellow users of MATLAB, I recently started using MATLAB ( for this subject) . I am having this error while executing the GUI file. Can someone please help me in solving this error.

Thankyou.

Best Regards.

Code:

% UIWAIT makes CourseworkGui wait for user response (see UIRESUME)

% uiwait(handles.figure1);

% --- Outputs from this function are returned to the command line.

function varargout = CourseworkGui_OutputFcn(hObject, eventdata, handles)

% varargout cell array for returning output args (see VARARGOUT);

% hObject handle to figure

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

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

% Get default command line output from handles structure

varargout{1} = handles.output;

% --- Executes on button press in pushbutton1.

function pushbutton1_Callback(hObject, eventdata, handles)

[filename, pathname] = uigetfile('*.*'); % Open a file browser

if filename == 0 % If the user didn't choose an image

disp("Please, select an image.");

else

handles.image_name = filename; % Put the file name to handles

handles.image_path = pathname; % Put the file path to handles

handles.image = imread(handles.image_name); % Read the image

imshow(handles.image, 'parent', handles.axes1) % Display the image on the axes1

guidata(hObject, handles); % Save the handles info.

end

% --- Executes on button press in pushbutton2.

function pushbutton2_Callback(hObject, eventdata, handles)

tempImg = handles.image;

[x, y, z] = size(tempImg); % Get a dimension of the image.

% If the image is colour, the image will be converted to grayscale image

if z == 3

handles.image = rgb2gray(tempImg); % RGB colour to grayscale

guidata(hObject, handles); % Save the handles info.

end

imshow(handles.image, 'parent', handles.axes1) % Display the image on the axes1

% --- Executes on selection change in popupmenu1.

function popupmenu1_Callback(hObject, eventdata, handles)

val = get(hObject, 'Value'); % Get the selected value on the pop up menu

handles.dctType = val; % Set the forward-DCT type

guidata(hObject, handles); % Save the handles info.

% --- Executes during object creation, after setting all properties.

function popupmenu1_CreateFcn(hObject, eventdata, handles)

% Hint: popupmenu controls usually have a white background on Windows.

% See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

set(hObject,'BackgroundColor','white');

end

% --- Executes on button press in pushbutton3.

function pushbutton3_Callback(hObject, eventdata, handles)

% Jpeg Compresstion [flattened Image] = JpegCompression(ImageName, Compresstion rate, DCT type, I-DCT type)

newImg = py.myJpeg.JpegCompression(handles.image_name, handles.compression_rate, handles.dctType, handles.idctType);

% reshape the flattened image to 2D or 3D image

[x, y, z] = size(handles.image); % Get a dimension of the image.

newImg = reshape(cellfun(@uint8, cell(newImg)), x, y, z);

imshow(newImg, 'parent', handles.axes2) % Display the image on the axes2

handles.newImage = newImg; % Put the JPEG image to handles

% Display count to know the process finished

handles.count = handles.count + 1;

str = sprintf("Test-%d", handles.count);

set(handles.edit3, 'String', str);

guidata(hObject, handles); % Save the handles info.

% --- Executes on button press in pushbutton4.

function pushbutton4_Callback(hObject, eventdata, handles)

image = handles.newImage;

if image == 0 % If there is no JPEG image data

disp("There is no image data.");

else

% Open the browser to get the file name and the path the user selected

[filename, pathname] = uiputfile('.jpeg');

% Check the file name whether the user puts the file name or not

if filename ~= 0

filepath = strcat(pathname, filename); % Make whole file path with the file name

imwrite(image, filepath); % Save the image

end

end

% --- Executes during object creation, after setting all properties.

function axes1_CreateFcn(hObject, eventdata, handles)

handles.axes1 = gca; % Get the handle of axes1

set(handles.axes1, 'XColor','none','YColor','none'); % Set the axes1 properties

guidata(hObject, handles); % Save the handles info.

% --- Executes during object creation, after setting all properties.

function axes2_CreateFcn(hObject, eventdata, handles)

handles.axes2 = gca; % Get the handle of axes2

set(handles.axes2, 'XColor','none','YColor','none'); % Set the axes2 properties

guidata(hObject, handles); % Save the handles info.

function edit1_Callback(hObject, eventdata, handles)

filename = get(hObject, 'String'); % Get the selected value on the pop up menu

handles.newImage_name = filename; % Set the new image name

guidata(hObject, handles); % Save the handles info.

% Hints: get(hObject,'String') returns contents of edit1 as text

% str2double(get(hObject,'String')) returns contents of edit1 as a double

% --- Executes during object creation, after setting all properties.

function edit1_CreateFcn(hObject, eventdata, handles)

% hObject handle to edit1 (see GCBO)

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

% handles empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.

% See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

set(hObject,'BackgroundColor','white');

end

% --- Executes on button press in pushbutton5.

function pushbutton5_Callback(hObject, eventdata, handles)

image = handles.newImage;

imagepath = handles.image_path;

imagename = handles.newImage_name;

imageformat = handles.newImage_format;

if image == 0 % Check the image array

disp("There is no image data.");

else

if isempty(imagename) == 1 % Check if the user put the file name or not

disp("Please, enter the file name.")

else

% Make file name with the JPEG compression information

% (image path + image name + compression rate + DCT type + IDCT type + file format)

filename = sprintf('%s%s_K%.0f_D%d_ID%d.%s', imagepath, imagename, handles.compression_rate, handles.dctType, handles.idctType, imageformat);

imwrite(image, filename);

end

end

% --- Executes on button press in radiobutton1.

function radiobutton1_Callback(hObject, eventdata, handles)

% User selected JPG image format

if (get(handles.radiobutton1, 'Value')) % Get the radio button handle and set the others off

set(handles.radiobutton2, 'Value', 0)

set(handles.radiobutton3, 'Value', 0)

handles.newImage_format = "jpg"; % Set the image format JPG

guidata(hObject, handles); % Save the handles info.

end

% Hint: get(hObject,'Value') returns toggle state of radiobutton1

% --- Executes on button press in radiobutton2.

function radiobutton2_Callback(hObject, eventdata, handles)

% hObject handle to radiobutton2 (see GCBO)

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

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

% User selected BMP image format

if (get(handles.radiobutton2, 'Value')) % Get the radio button handle and set the others off

set(handles.radiobutton1, 'Value', 0)

set(handles.radiobutton3, 'Value', 0)

handles.newImage_format = "bmp"; % Set the image format BMP

guidata(hObject, handles); % Save the handles info.

end

% Hint: get(hObject,'Value') returns toggle state of radiobutton2

% --- Executes on button press in radiobutton3.

function radiobutton3_Callback(hObject, eventdata, handles)

% hObject handle to radiobutton3 (see GCBO)

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

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

% User selected JPEG image format

if (get(handles.radiobutton3, 'Value')) % Get the radio button handle and set the others off

set(handles.radiobutton1, 'Value', 0)

set(handles.radiobutton2, 'Value', 0)

handles.newImage_format = "jpeg"; % Set the image format JPEG

guidata(hObject, handles); % Save the handles info.

end

% Hint: get(hObject,'Value') returns toggle state of radiobutton3

% --- Executes on button press in pushbutton6.

function pushbutton6_Callback(hObject, eventdata, handles)

% hObject handle to pushbutton6 (see GCBO)

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

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

figure('Name','Quantization Table','NumberTitle','off')

image(handles.quantization_table);

% --- Executes on slider movement.

function slider1_Callback(hObject, eventdata, handles)

% hObject handle to slider1 (see GCBO)

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

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

val = get(hObject, 'Value'); % Get the selected value on the pop up menu

handles.compression_rate = val; % Set the compression rate

set(handles.edit2, 'String', sprintf('%.2f', val)); % Display compression rate on the edit box

guidata(hObject, handles); % Save the handles info.

% Hints: get(hObject,'Value') returns position of slider

% get(hObject,'Min') and get(hObject,'Max') to determine range of slider

% --- Executes during object creation, after setting all properties.

function slider1_CreateFcn(hObject, eventdata, handles)

% hObject handle to slider1 (see GCBO)

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

% handles empty - handles not created until after all CreateFcns called

% Hint: slider controls usually have a light gray background.

if isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

set(hObject,'BackgroundColor',[.9 .9 .9]);

end

function edit2_Callback(hObject, eventdata, handles)

% hObject handle to edit2 (see GCBO)

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

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

% Hints: get(hObject,'String') returns contents of edit2 as text

% str2double(get(hObject,'String')) returns contents of edit2 as a double

str = get(handles.edit2, 'String'); % Get the compression rate

val = str2double(str); % Convert the string type to double type

if val >= 0.0 && val <= 100.0 % Check if the compression rate exceed the limit or not

handles.compresstion_rate = val; % Set the compression rate

guidata(hObject, handles); % Save the handles info.

set(handles.slider1, 'Value', val); % Move the slider bar on proper position

else

disp("Error : invalid value.");

end

% --- Executes during object creation, after setting all properties.

function edit2_CreateFcn(hObject, eventdata, handles)

% hObject handle to edit2 (see GCBO)

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

% handles empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.

% See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

set(hObject,'BackgroundColor','white');

end

% --- Executes on selection change in popupmenu3.

function popupmenu3_Callback(hObject, eventdata, handles)

% hObject handle to popupmenu3 (see GCBO)

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

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

val = get(hObject, 'Value'); % Get the selected value on the pop up menu

handles.idctType = val; % Set the inverse-DCT type

guidata(hObject, handles); % Save the handles info.

% Hints: contents = cellstr(get(hObject,'String')) returns popupmenu3 contents as cell array

% contents{get(hObject,'Value')} returns selected item from popupmenu3

% --- Executes during object creation, after setting all properties.

function popupmenu3_CreateFcn(hObject, eventdata, handles)

% hObject handle to popupmenu3 (see GCBO)

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

% handles empty - handles not created until after all CreateFcns called

% Hint: popupmenu controls usually have a white background on Windows.

% See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

set(hObject,'BackgroundColor','white');

end

function edit3_Callback(hObject, eventdata, handles)

% hObject handle to edit3 (see GCBO)

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

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

% Hints: get(hObject,'String') returns contents of edit3 as text

% str2double(get(hObject,'String')) returns contents of edit3 as a double

% --- Executes during object creation, after setting all properties.

function edit3_CreateFcn(hObject, eventdata, handles)

% hObject handle to edit3 (see GCBO)

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

% handles empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.

% See ISPC and COMPUTER.

if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))

set(hObject,'BackgroundColor','white');

end

Error:

Unable to resolve the name py.myJpeg.JpegCompression.

Error in CourseworkGui>pushbutton3_Callback (line 144)

newImg = py.myJpeg.JpegCompression(handles.image_name, handles.compression_rate, handles.dctType,

handles.idctType);

Error in gui_mainfcn (line 95)

feval(varargin{:});

Error in CourseworkGui (line 42)

gui_mainfcn(gui_State, varargin{:});

Error in

matlab.graphics.internal.figfile.FigFile/read>@(hObject,eventdata)CourseworkGui('pushbutton3_Callback',hObject,eventdata,guidata(hObject))

Error while evaluating UIControl Callback.

[Sivani Pentapati]

From my understanding, you are facing error because of the py.myJpeg.JpegCompression function. Could you provide more information about the compression function so that I can replicate the issue.