vlt.image.corrcoef

  CORRCOEF - Computes a 2D spatial cross-correlation coefficient map.

    C = vlt.image.corrcoef(IMAGE1, IMAGE2, MASK1, MASK2, N)

    Calculates the 2D cross-correlation coefficient between two images for a
    range of spatial shifts up to N pixels in x and y. The correlation is
    only computed over pixels that are valid in both provided masks.

    The function leverages the symmetry of the correlation coefficient,
    C(dy, dx) = C(-dy, -dx), to reduce computations by about half.

    Inputs:
      IMAGE1 - The first 2D data matrix.
      IMAGE2 - The second 2D data matrix, must be the same size as IMAGE1.
      MASK1  - A logical matrix of the same size as IMAGE1. True values
               indicate valid pixels to be included in the correlation.
      MASK2  - A logical matrix for IMAGE2, same size and meaning as MASK1.
      N      - A scalar integer specifying the maximum shift in pixels for
               the correlation calculation. The output will be (2N+1)x(2N+1).

    Outputs:
      C      - A (2N+1)x(2N+1) matrix containing the correlation coefficients.
               The center of the matrix (C(N+1, N+1)) corresponds to a
               zero-pixel shift.

    Example:
      img = rand(100);
      img_shifted = circshift(img, [5 10]);
      mask = true(100);
      C = vlt.image.corrcoef(img, img_shifted, mask, mask, 20);
      figure;
      imagesc(-20:20, -20:20, C);
      colorbar;
      title('Spatial Cross-Correlation');
      xlabel('X Shift (pixels)'); ylabel('Y Shift (pixels)');