idct (Signal Processing Toolbox)

Inverse discrete cosine transform.

Syntax

x = idct(y)
x = idct(y,n)

Description

The inverse discrete cosine transform reconstructs a sequence from its discrete cosine transform (DCT) coefficients. The idct function is the inverse of the dct function.

x = idct(y) returns the inverse discrete cosine transform of y

where

and N = length(x), which is the same as length(y). The series is indexed from n = 1 and k = 1 instead of the usual n = 0 and k = 0 because MATLAB vectors run from 1 to N instead of from 0 to N-1.

x = idct(y,n) appends zeros or truncates the vector y to length n before transforming.

If y is a matrix, idct transforms its columns.

See Also

dct
Discrete cosine transform (DCT).

dct2
Two-dimensional DCT (see the Image Processing Toolbox documentation).

idct2
Two-dimensional inverse DCT (see the Image Processing Toolbox documentation).

ifft
One-dimensional inverse fast Fourier transform.

`dct`	Discrete cosine transform (DCT).
`dct2`	Two-dimensional DCT (see the Image Processing Toolbox documentation).
`idct2`	Two-dimensional inverse DCT (see the Image Processing Toolbox documentation).
`ifft`	One-dimensional inverse fast Fourier transform.

References

[1] Jain, A.K., Fundamentals of Digital Image Processing, Prentice-Hall, 1989.

[2] Pennebaker, W.B., and J.L. Mitchell, JPEG Still Image Data Compression Standard, Van Nostrand Reinhold, 1993, Chapter 4.

icceps ifft