This paper describes the band-splitting properties of the discrete cosine transform (DCT). The one-dimensional DCT, viewed as a filter, can split the filtered output into two halves, one corresponding to the low-frequency band of the input and the other to the high-frequency band of the input. In a two-dimensional case, the DCT behaves like a quadrature mirror filter. Based on the band-splitting properties of the DCT, a dual-mode image compression method has emerged. This new method is used to quantize and encode the image edges in the spatial domain and the uniform image portions in the DCT frequency domain. Analysis and simulation are included herein. Improvement of image quality by the use of this new method has been demonstrated through simulation.

Date Published: 16 December 1988
PDF: 15 pages
Proc. SPIE 0974, Applications of Digital Image Processing XI, (16 December 1988); doi: 10.1117/12.948436

Published in SPIE Proceedings Vol. 0974:
Applications of Digital Image Processing XI
Andrew G. Tescher, Editor(s)