【摘要】 提出了一种新的 H.2 63码率控制策略 .该策略利用人眼对图像低频分量比对高频分量敏感的特性 ,先对图像进行预处理 ,去掉部分高频分量 ,并在量化时引入视觉特性因子以加大图像复杂区的量化而减小图像平坦区的量化 .在码率一定的情况下 ,通过加大高频分量的失真 ,降低其所占码率 ,可以相应地分配更多码字给低频分量 ,从而减小低频分量失真 .试验结果表明 :通过各种失真进行加权折衷 ,新的算法能够减小低码率图像编码中的块效应 ,改善图像的主观质量更多还原

【Abstract】 A new rate control strategy for H.263 was proposed. As human eyes are more sensitive to the low coefficients than to the high coefficients, a preprocessor is employed to remove part of the high coefficients and a visual property factor is introduced to increase the quantization step in complex regions while decreasing the quantization step in flat regions. In this way, the distortion of high coefficients is increased by allocating less bits to them while the distortion of low coefficients is reduced relatively by allocating more bits to them when the total bit rate is constant. The simulation result shows that this new strategy can reduce the blocking effects and achieve a better subjective image quality by making a trade off among all kinds of distortion.更多还原