The Discrete Cosine Transform (
DCT) is a method of reformating data which helps separate an
image into
spectral sub-bands of differing importance. The DCT is similar to the Discrete
Fourier Transform (
DFT) in that it transforms a signal or image from the
spatial domain to the
frequency domain. However, the DCT does a better job of concentrating energy into lower order
coefficients the
DFT for
image data.
This is one part in several steps to generating a JPEG or MPEG compressed file.