On Asymmetrical Performance of Discrete Cosine Transform

The Discrete Cosine Transform (DCT) [1] is considered as a suboptimum transform for many practical source coding applications. Autoregressive, order 1, AR(1) source models are good first approximations to several natural signals. It is known that the performance of DCT depends on the sign of the autocorrelation coefficient of AR(1) source. This correspondence explains theoretically the asymmetrical performance of DCT along with the Modified Hermite Transform (MHT) [2] and Discrete Hadamard Transform (DHT) which performs symmetrically regardless of the sign of autocorrelation coefficient.