基于部分位平面交替偏移的感兴趣区图像编码

提出一种基于部分位平面交替的感兴趣区（ROI）图像编码方式-PBAshift。采用4个策略提高编码效率：1）向上偏移最重要ROI位平面至最大背景（BG）位平面之上，保证最重要ROI位平面得到优先编码；2）将最重要的BG位平面与一般重要ROI位平面交替偏移；3）重要性一般的BG位平面与重要性最差的ROI位平面不偏移；4）向下偏移重要性最差的BG位平面。实验表明，PBAShift不仅支持元需ROI形状信息的单ROI编码，而且支持不同兴趣度下的多ROI编码，对今后医药与遥感图像压缩具有重要意义。

Region of Interest Image Coding Based on Partial Bitplanes Alternating Shift

A Region of interest(ROI) image coding method based on partial bitplanes alternating shift(PBAShift) is presented.Four strategies are introduced to improve the coding efficiency.First,the most significant bitplanes of ROI are shifted upon the maximum bitplane of background(BG).It can ensure the most significant bitplanes of ROI are firstcaoded.Second,the most significant bitplanes of BG coefficients and the general significant bitplanes of ROI are shifted up by bitplane-by-bitplane alternating scaling.Third,the general significant bitplanes of BG and the least significant bitplanes of ROI are obtained in the original positions.Finally,the least significant bitplanes of BG are shifted down.The experiments show that the PBAShift supports not only arbitrary shape single ROI coding without any ROI shape information,but also multiple ROIs coding with different degrees of interest.So the new method is valuable for medical and remote sensing image compression.