Adaptive Block Cosine Transform Coding Using A New Quantization Algorithm
Hisashi Yonekawa, Yoshiyuki Ishimitsu, Junichirou Akune, Hiroshi Takeuchi · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1989
We have studied the problem of adaptive cosine transform coding, and developed an original quantization algorithm which can minimize block artifacts. There are three features in our compression technique. The first feauture is variable quantization interval. The quantization interval is determined adaptively depending on the statistical characteristics of the block. In our technique, the number of AC components which are rounded off to zero by quantization is used for the quantization parameter. The second feature is the adaptive cutoff of the high frequency components of the transform coefficients. High frequency components may be ignored adaptively in our technique. The third feature is the double quantization algorithm. Non-adaptive quantization is carried out first. The second quantization is performed adaptively.