Hello, I am attempting to correlate an image drawn from a video with a cropped out portion of the same image. We are having dimension problems that wont seem to go away. I believe that there may be some underlying problem that I am not recognizing. Any help is appreciated, I have posted the code below. Unfortunately the Mp4 file we used is too large to attach, but this code should operate the same for any video file.
function[] = Again(~)
prompt = 'Name of file?\n'; %Prompt user to input a video file.
result = input(prompt);
%Step through the video frame by frame. We chose 58 as an arbitrary point %to stop where we know a good variety of objects are present.
videoFReader = vision.VideoFileReader(result);
videoPlayer = vision.VideoPlayer;
j = 0;
while j<58;
%while ~isDone(videoFReader)
videoFrame = step(videoFReader);
step(videoPlayer,videoFrame);
j=j+1;
i=step(videoFReader);
hold on
end
%imtool(i);
%Crop out a section of image(i) and assign it variable h. Here we did it in %two seperate ways, just for fun...
%h=imcrop(i,[1016 488 219 157]);
h = i(488:645,1016:1235,3);
h(720,1280,3)= 0; %Ensure image dimensions of i and h match
imshow (h); %Now the hat is red?
figure, imshow (i);
%Here we used the ndims, length, & numel functions to determine if each image %has the desired matrix dimensions and more importatntly that they are %identicle.
%ndims(i)
%length(i)
%numel(i)
%ndims(h)
%length(h)
%numel(h)
%In our first attempt to correlate two images we chose to first attempt to %use both magnitude and phase. However now we are attempting to us only the %phase to correlate the images and create a mesh to show any matches. We %have included both attempts although neither work. Each returns similar %errors about the matrix dimensions of the two files.
%********************* Attemp to coorrelate #1*****************************
%To ensure the the cropped image has the same dimensions %as image i, we include the 720,1280
I = fft2(i);
H = fft2(h,720,1280);
%Here is what we beleive to be two functional ways to extract the phase %information the fourier transfor of an image. We chose the latter for %simplicity.
%F_Phase = cos(angle(I)) + j*(sin(angle(I)));
%F_Phase2 = cos(angle(H)) + j*(sin(angle(H)));
F_Phase = exp(1j*angle(I));
F_Phase2 = exp(1j*angle(H));
%This is what we beleive would be the way to correlate two images based on %phase and magnitude information.
%conjH=conj(H);
%R = I .* conjH;
%We have read that correlation is like convlution but rotated 180 degrees, % and mathmatically it makes sense. However this is where the error occur. % The error we get regularily is that "The Matrix sizes must be the same" % despite the images being the same dimensions.
R = F_Phase .* (rot90(F_Phase2,2));
%Here we take the inverse fourier transform and set it to real values so %that we may view the results using the mesh function.
res=real(ifft2®);
%size(res)
mesh(res);
%*************************************************************************
%Release the video player and reader.
release(videoPlayer);
release(videoFReader);
end
