what is DCT (or IDCT)? - DCT is a transform that converts a set of frequency coefficients to a signal. for an image, this transform is performed on a 2 dimensional array of coefficients, resulting in a 2 dimensional array of samples. the data input into the core and output from the core takes place as a block of 8x8 samples DCT: discrete cosine transform [www.ece.purdue.edu/~ace/jpeg-tut/jpgdct1.html dctequation] IDCT: inverse DCT (to uncompress)
which is one element of mpeg4/proposed compresion alongside objects/motion (what else?)
also digitalvideoprocessing.pdf
http://wwwam.hhi.de/mpeg-video/standards/mpeg-4.htm note DCT is used in JPEG