中文摘要：

高清、超高清视频编解码芯片结构设计中，原始图像帧和解码图像参考帧都存在外部存储器，外存访问带宽是系统设计的一大难题。通过图像压缩编码技术来降低图像冗余度，从而减小图像的存储容量和传输带宽。针对这一问题，提出了一种改进型无损图像压缩算法。与已有无损压缩算法相比，改进后算法以宏块为预测编码的基本单元，支持宏块随机访问；首先在预测部分加入块级预测与分层预测的自适应选择；然后在编码部分融入两种预测模式的半定长变长编码。实验结果表明，可降低带宽约50％。

英文摘要：

In HD and Ultra HD video decode chip design, the original image and the decoded image reference frames are stored in the external memory. The external memory access bandwidth is the major problem in the system design. The image compression technology can be used to reduce image redundancy to compress the saving size. We proposed an improved lossless image compression algorithm. The predictive coding unit of the algorithm was macrolock supporting random access. The adaptive choice of hierarchical and block-level prediction was added to the forecast section; and a hierarchical half-length VLC coding was added to the coding part. The bandwidth can reduce about 50%.