自适应率失真跟踪ROI编码方法

针对系数提升ROI算法的固有缺点,提出了一种基于率失真优化截取内嵌码块编码(EBCOT)算法的医疗图像矩形感兴趣区域(ROI)编码方法。区别于JPEG2000标准建议,算法不是通过对医疗图像中关键诊断区域的小波系数比特平面移位实现,而是提升码块的率失真斜率通过码流优化截取来实现ROI编码,从而使系统具有更高的压缩比和更低算法复杂度,并通过自适应误差跟踪获得图像的ROI和BG(背景)的质量可任意控制的特性。用该方法对多幅CT图像进行测试,结果表明:该方法可在保证关键诊断区域无损或近无损条件下提高压缩比8-40倍,完全继承JPEG2000在远程医疗系统中的各种优良应用特性,更好地解决医疗图像在存储和传输过程中数据量过大的难题。

ROI coding method for adaptive rate-distortion tracing

Many current compression schemes provide a very high compression rate but with considerable loss of quality.On the other hand,in some areas in medicine,it may be sufficient to maintain high image quality only in ROI(the region of interest),i.e.,in diagnostically important regions.A hybrid scheme of lossless compression in the region of interest is discussed,with high-rate lossy compression in other regions.The new ROI coding method is based on EBCOT(embedded block coding with optimized truncation),which enables flexible adjustment of compression quality in the ROI and BG and keeps all the features of JPEG2000.Because the method needs not to lift and reversely lift the coefficients,the method can also get the higher compression ratio and less computing complexity.It has been evaluated on medical CT images,the experimental results have been proved to be very encouraging.