Calculates the 2D Inverse Discrete Cosine Transform.
IDCT2(array, nr, nc)
array |
- |
A multi-column series or expression resulting in a multi-column series. |
nr |
- |
Optional. An integer, the number of rows. Defaults to row length of input array. |
nc |
- |
Optional. An integer, the number of columns. Defaults to column length of input array. |
An array.
W1: ravel(gcos(100, 1/100, 3), 10)
W2: dct2(W1)
W3: idct2(W2)
returns the original array (within roundoff error).
IDCT2 is often used in conjunction with DCT2 to perform image compression.
[1] Jae S. Lim,
Two-dimensional Signal and Image Processing
pp. 148-162 Implements an even-symmetrical DCT
[2] Jain,
Fundamentals of Digital Image Processing
pp. 150-153
[3] Wallace,
The JPEG Still Picture Compression Standard
Communications of the ACM, April 1991