"Undefined function or variable "o1Bound" " whereas that variable have been used in another function and it works, how can I fix this error ?

I got the code from here http://www.comp.hkbu.edu.hk/~vincent/resTool.htm (fingerprint verification) and I implement this in my project

% --- Executes on button press in btn_direction.
function btn_direction_Callback(hObject, eventdata, handles)
image1 = handles.image1;
guidata(hObject,handles);
axes(handles.axes2);
[o1Bound,o1Area]=direction(image1,16);
guidata(hObject,handles);

% --- Executes on button press in btn_ROI.
function btn_ROI_Callback(hObject, eventdata, handles)
image1 = handles.image1;
guidata(hObject,handles);
axes(handles.axes2);
[o2,o1Bound,o1Area]=drawROI(image1,o1Bound,o1Area);
guidata(hObject,handles);

the error is on this line > [o2,o1Bound,o1Area]=drawROI(image1,o1Bound,o1Area);

Answer 1

[Geoff Hayes]

Faza - the scope for the variables o1Bound and 01Area is local to the btn_direction_Callback function only and so are not available to any other function. What you can do instead is to save these variables to the handles structure and access them through it in the other callback. For example,

function btn_direction_Callback(hObject, eventdata, handles)
if isfield(handles,'image1')
    axes(handles.axes2);
    [o1Bound,o1Area]=direction(handles.image1,16);
    handles.o1Bound = o1Bound;  % add the two fields to handles
    handles.o1Area  = o1Area;
    guidata(hObject,handles);   % save the updated handles structure
end

Now, in your second callback you would do the following

function btn_ROI_Callback(hObject, eventdata, handles)
if isfield(handles,'image1') && isfield(handles,'o1Bound') && isfield(handles,'o1Area)
    axes(handles.axes2);
    [o2,o1Bound,o1Area]=drawROI(handles.image1,handles.o1Bound,handles.o1Area);
    % do you need to save the output of drawROI??
end

Note how the isfield function to check to see if the variable that we want to access is a field within the handles structure. We use guidata only when we want to save the updated handles structure to the hObject (parent) figure.

[Faza Faridah]

thanks Geoff, it really works in my project.