Chromatic Res. Inc., Sunnyvale, CA.
IEEE Trans Image Process. 1997;6(3):441-50. doi: 10.1109/83.557354.
An adaptive vector quantization (VQ) scheme with codebook transmission is derived for the variable-rate source coding of image data using an entropy-constrained Lagrangian framework. Starting from an arbitrary initial codebook C(I) available to both the encoder and decoder, the proposed algorithm iteratively generates an improved operational codebook C(0) that is well adapted to the statistics of a particular image or subimage. Unlike other approaches, the rate-distortion trade-offs associated with the transmission of updated code vectors to the decoder are explicitly considered in the design. In all cases, the algorithm guarantees that the operational codebook C(0) will have rate-distortion performance (including all side-information) better than or equal to that of any initial codebook C(I). When coding the Barbara image, improvement at all rates is demonstrated with observed gains of up to 3 dB in peak signal-to-noise ratio (PSNR). Whereas in general the algorithm is multipass in nature, encoding complexity can be mitigated without an exorbitant rate-distortion penalty by restricting the total number of iterations. Experiments are provided that demonstrate substantial rate-distortion improvement can be achieved with just a single pass of the algorithm.
一种自适应矢量量化（VQ）方案与码本传输是派生的变比特率源编码的图像数据使用熵约束拉格朗日框架。从任意初始码本 C（I）可利用编码器和解码器，提出的算法迭代地产生一个改进的操作码本 C（0）是很好的适应统计数据的一个特定的图像或子图像。与其他方法不同，速率失真折衷与传输更新码向量的解码器是明确考虑在设计中。在所有情况下，该算法保证操作码本 C（0）将具有率失真性能（包括所有附加信息）优于或等于任何初始码本 C（I）。当编码的芭芭拉图像，改善在所有的速度都证明了观察增益高达 3 分贝的峰值信噪比（PSNR）。而在一般的算法是多通道的性质，编码复杂度可以减轻而不挥霍率失真惩罚限制总迭代次数。实验表明，实现了显著的速率失真改善，可以用仅仅一个通过该算法。
