支持可变分辨率的SPIHT编码算法

A SPIHT Coding Algorithm for Variable Resolution Display

为了适应移动多媒体通信中终端设备显示尺寸多样性的要求,本文将图像缩放嵌入编码过程中,提出了一种基于线裁剪(seam carving,SC)的支持可变分辨率的多级树集合排序(set portioning in hierarchical trees,SPIHT)图像编码算法。该算法在构造新的基于根节点的空间方向树的基础上,利用SC生成基于块的线能量图来引导编码,获得空域可伸缩的码流;解码端仅需获取与终端设备显示尺寸相关的码流即可完成解码和图像缩放。实验结果表明,当编码和解码图像的分辨率一致时,本文算法的率失真(rate-distortion,R-D)性能逼近传统的SPIHT算法;当解码图像的分辨率可变时,本文算法在压缩码率与重建图像的主观质量上均优于传统的SPIHT算法。

To meet the requirement of various resolution displays on mobile terminals, an improved set portion in hierarchi- cal trees （SPIHT） image coding algorithm is proposed, which integrates the seam carving （SC） technique. In the presen- ted method, to generate spatial scalable bit stream, a new structure of spatial orientation tree （SOT） based on root nodes is constructed and the SC is used as a guide for SPIHT coding procedure. Mobile receivers can be capable of finishing the compression decoding and image resizing simultaneously only requiring the corresponding bit stream by using the proposed algorithm. Experimental results show that when the target resolution of receiver is the same as the original resolution, the average rate-distortion （R-D） performance of the proposed method is much close to that of the traditional SPIHT coding al- gorithm. While the target resolutions are lower than the original resolution, the proposed algorithm is superior to the tradi- tional SPIHT coding approach whatever for coding bit rates or subjective quality of reconstructed images.