2D cross correlation unable to match

HI,

i am trying to compare 2 images using corr2 . When i compare with the first image in the folder, an error message is prompt which is what i wanted. But when the 2nd image in the folder is used to compare, it states that there is no match. I am not sure where went wrong, the 2nd image is already in the folder and its exactly the same but there is no match.

% --- Executes on button press in btnSelectFolder.
function btnSelectFolder_Callback(hObject, eventdata, handles)
% hObject    handle to btnSelectFolder (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

[filename, pathname] = uigetfile({'*.png;', 'All Image Files (*.png)'; ...
      '*.*',                   'All Files (*.*)'}, ...
    'Pick an image file');

if filename ~= 0
FileName = fullfile(pathname,filename);
end
if pathname==0,
    return; 
end  
axes (handles.axes1);
queryFace= imread (FileName);
queryFaceresize=imresize(queryFace,[240,240]);
imshow(queryFaceresize, 'Parent', handles.axes1);
faceDetector=vision.CascadeObjectDetector('FrontalFaceCART');
bbox = step(faceDetector,queryFace);
axes (handles.axes1);
if  size(bbox,1) == 0
    errordlg('No face detected.Please upload another one.');
    return;
elseif size(bbox,1)>1
    errordlg('Too many face detected. Please upload another one')
    return;
else
   path='C:\Users\ET\Desktop\matlab\project\Database\';
   list=dir([path, '*.png']);
   img=imread(FileName);
   newimg=imresize(img,[240 240]);
   X1=rgb2ind(newimg,16);
   for x=1:length(list)
    images{x}=imread([path, list(x).name]);
    X2=rgb2ind(images{x},16);
    newX2=imresize(X2,size(X1));
    c=corr2(X1,newX2);
    if c==1
       errordlg('Image Error. Please upload another one');
        return;  
    else
        msgbox('Please click the save button to save your image into our system.');
        set(handles.saveImage,'Visible','on');
        return;
    end
   end
end
please help!
thank you!

[Geoff Hayes]

Eliza - put a breakpoint at the line

 for x=1:length(list)

and then run your code. When the debugger pauses at this line, start stepping through the code and look at each variable to ensure that it makes sense. What are X1 and newX2? Display each image using imshow to see each one. After the correlation, what is c?

Answer 1

[Image Analyst]

Perhaps you really meant to use normxcorr2(). See attached demo.