Signal Processing Toolbox
  Go to function:
    Search    Help Desk 
idct    See Also

Inverse discrete cosine transform.

Syntax

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 Image Processing Toolbox User's Guide).
idct2
 Two-dimensional inverse DCT (see Image Processing Toolbox User's Guide).
ifft
 One-dimensional inverse fast Fourier transform.

References

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

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


[ Previous | Help Desk | Next ]