DCT2

Purpose:

Calculates the 2D Discrete Cosine Transform.

DCT2(array, nr, nc)

array	-	An input array.
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).

DCT2 is often used in conjunction with IDCT2 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