Rate control method for B-spline picture coding

As a coding algorithm in which picture processing can be applied directly to the compressed data, the author has proposed a surface-fitting method (B-spline coding) for the variation of the pixel values using the B-spine surfaces. It was shown that the performance of the new algorithm is equal to or better than the one in the DCT system, even for the compression efficiency. On the other hand, in some compression coding systems dealing with picture data, it is required that the coding is completed for one picture at a predetermined rate. Such problems of controlling the coding rate have not been studied for B-spline coding. In this paper, a method is proposed for dealing with the above problems. In addition, an effort is made to enhance the performance of B-spline surfaces as a compression tool. In this paper, the number of coded bits of each block is controlled by adaptive feedback, depending on the fineness of the picture pattern and the actual number of coded bits generated. A performance evaluation shows that the deviation of the actual number of coded bits from the specified number can be kept within 1%, while the compression performance (better than that of the DCT system) is maintained, and that coding rate control is possible in B-spline coding. (C) 1997 Scripta Technica, Inc.