Help with block matching (full search) algorithm

Hi, starting from this post, I am trying to implement a block matching full search algorithm. However I have an error (Subscript indices must either be real positive integers or logicals.) that I can't fix. Also I'd need some help to plot the final image with the vectors using the quiver function.

Thank you.

Here's my code

clear;
clc;

blockMatching('DatasetB.avi',200, 16, 20);

% The function parameters are:
% - video_path: video source
% - index: frame number
% - N: block size
% - R: search range

function motionVect = blockMatching(video_path, index, N, R)

VidObj = VideoReader(video_path);
% get 2 consecutive frames
f1 = read(VidObj, index);
f2 = read(VidObj, index+1);

[height, width] = size(f2);

for i = 1:N:height-N
    for j = 1:N:width-N

          MAD_min = 256*N*N;
          mvx = 0;
          mvy = 0;

          for k = -R:1:R
              for l = -R:1:R
                  MAD = sum(sum(abs(f1(i:i+N-1, j:j+N-1) - f2(i+k:i+k+N-1, j+l:j+l+N-1))));

                  if (MAD < MAD_min)
                      MAD_min = MAD;
                      dy = k;
                      dx = l;
                  end

              end
          end

          fp(i:i+N-1, j:j+N-1) = f2(i+dy:i+dy+N-1, j+dx:j+dx+N-1);        
          iblk = floor((i-1)/(N+1));
          jblk = floor((j-1)/(N+1));
          mvx(iblk, jblk) = dx;
          mvy(iblk, jblk) = dy;

      end
  end

end

Answer 1

[Martin Waciewski]

You should first convert the frames into grayscale by using rgb2gray. And i = 1 - 20 is negative