c=dgt2(f,g,a,M); c=dgt2(f,g1,g2,[a1,a2],[M1,M2]); c=dgt2(f,g1,g2,[a1,a2],[M1,M2],[L1,L2]); [c,Ls]=dgt2(f,g1,g2,[a1,a2],[M1,M2]); [c,Ls]=dgt2(f,g1,g2,[a1,a2],[M1,M2],[L1,L2]);
| f | Input data, matrix. |
| g, g1, g2 | |
| Window functions. | |
| a, a1, a2 | |
| Length of time shifts. | |
| M, M1, M2 | |
| Number of modulations. | |
| L1, L2 | Length of transform to do |
| c | array of coefficients. |
| Ls | Original size of input matrix. |
dgt2(f,g,a,M) will calculate a separable two-dimensional discrete Gabor transformation of the input signal f with respect to the window g and parameters a and M.
For each dimension, the length of the transform will be the smallest possible that is larger than the length of the signal along that dimension. f will be appropriately zero-extended.
dgt2(f,g,a,M,L) computes a Gabor transform as above, but does a transform of length L along each dimension. f will be cut or zero-extended to length L before the transform is done.
[c,Ls]=dgt2(f,g,a,M) or [c,Ls]=dgt2(f,g,a,M,L) additionally returns the length of the input signal f. This is handy for reconstruction:
[c,Ls]=dgt2(f,g,a,M); fr=idgt2(c,gd,a,Ls);
will reconstruct the signal f no matter what the size of f is, provided that gd is a dual window of g.
dgt2(f,g1,g2,a,M) makes it possible to use a different window along the two dimensions.
The parameters a, M, L and Ls can also be vectors of length 2. In this case the first element will be used for the first dimension and the second element will be used for the second dimension.
The output c has 4 or 5 dimensions. The dimensions index the following properties: