idct2 {gsignal}

Inverse 2-D Discrete Cosine Transform

Description

Compute the inverse two-dimensional discrete cosine transform of a matrix.

Usage

idct2(x, m = NROW(x), n = NCOL(x))

Arguments

x

2-D numeric matrix

m

Number of rows, specified as a positive integer. dct2 pads or truncates x so that it has m rows. Default: NROW(x).

n

Number of columns, specified as a positive integer. dct2 pads or truncates x so that it has n columns. Default: NCOL(x).

Details

The discrete cosine transform (DCT) is closely related to the discrete Fourier transform. It is a separable linear transformation; that is, the two-dimensional transform is equivalent to a one-dimensional DCT performed along a single dimension followed by a one-dimensional DCT in the other dimension.

Value

m-by-n numeric discrete cosine transformed matrix.

Author(s)

Paul Kienzle, [e-mail].
Conversion to R by Geert van Boxtel, [e-mail].

See Also

dct2

Examples

A <- matrix(50 * runif(100), 10, 10)
B <- dct2(A)
B[which(B < 1)] <- 0
AA <- idct2(B)