Abstract-A new rate control algorithm for the H.264 encoder is developed in this work. There are several unique features in the proposed rate control scheme. First, a two-stage encoding mechansim is used to resolve the problem of inter-dependency between R-D optimization (RDO) and rate control (RC) in H.264. Second, it is emphasized that the bits of the header information may occupy a larger portion of the total bit budget especially when encoding at low bit rates in H.264. To address this issue, a rate model for the header information is established so as to estimate header bits more accurately. Third, a new source rate model is proposed to estimate the quantization parameter (QP) from the residual signal. Built upon the above ideas, a rate control algorithm is developed for the H.264 baseline-profile encoder under the constant-bit-rate (CBR) constraint. It is shown by experimental results that the proposed scheme can control bit rates accurately with the R-D performance better than that of the rate control algorithm implemented in H.264 JM8.1a.
A new blind inverse halftoning algorithm based on a nonlinear filtering technique of low computational complexity and low memory requirement is proposed in this research. It is called blind since we do not require the knowledge of the halftone kernel. The proposed scheme performs nonlinear filtering in conjunction with edge enhancement to improve the quality of an inverse halftoned image. Distinct features of the proposed approach include efficiently smoothing halftone patterns in large homogeneous areas, additional edge enhancement capability to recover the edge quality, and an excellent PSNR performance with only local integer operations and a small memory buffer. C 2001 Academic Press
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