Select Files with Specific File Types using Dialog Box in Matlab GUI

gistfile1.txt

function pushbutton2_Callback(hObject, eventdata, handles)
% above line of code is default line ofcode for button



% an example to open image files only 
% when button is clicked, a dialog box appears to select the file
handles.output = hObject;
[fn pn] = uigetfile( {  
   '*.png;*.jpg;*.jpeg;*.gif','Image Files (*.png, *.jpg, *.jpeg, *.gif)'; ...
   });