Region-of-interest coding in volumetric images with shape-adaptive wavelet transform
Region-of-interest coding in volumetric images with shape-adaptive wavelet transform
复制标题
使用形状自适应小波变换对体积图像进行感兴趣区域编码
DOI：
10.1117/12.476709
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
W. Pearlman
中科院分区：
文献类型：
--
作者：
I. Ueno;W. Pearlman
我们评估了一些任意形状的感兴趣区域（ROI）编码技术的三维体积图像，并通过观察，我们提出了一个灵活的ROI编码与有效的压缩性能。在任意形状的ROI编码中，图像中的对象与指示对象区域的形状信息一起以比图像的其余部分更高的保真度被编码。在我们提出的方法（命名为SA-ROI），其中形状自适应小波变换和基于缩放的ROI编码相结合，在目标内的样本进行三维形状自适应小波变换，根据其形状信息。如果需要，还独立地通过形状自适应小波变换对背景进行变换。然后，对象内的样本被按比例放大一定数量的移位，并且从MSB（最高有效位）逐平面地编码，使得对象内的系数被更早地编码并且具有比背景更高的保真度。与基于尺度变换的普通小波变换ROI编码相比，SA-ROI的无损压缩率提高了5%。同样在有损编码中，除了在非常低的编码速率下，SA-ROI具有更好的压缩性能。
We evaluated some arbitrary-shape ROI (Region of Interest) coding techniques for three-dimensional volumetric images, and through the observation we propose a flexible ROI coding with efficient compression performance. In arbitrary-shape ROI coding, the object in an image is coded with higher fidelity than the rest of the image, together with the shape information, which indicates the region of the object. In our proposed method (named as SA-ROI), in which shape-adaptive wavelet transform and scaling-based ROI coding are incorporated, the samples within the object are transformed with three-dimensional shape-adaptive wavelet transform according to its shape-information. If necessary, the background is also transformed by shape-adaptive wavelet transform independently. Then the samples within the object are scaled up by a certain number of bit-shifts, and encoded from the MSB (Most Significant Bit) plane by plane so that coefficients within the object are encoded earlier and have higher fidelity than the background. Compared with the scaling-based ROI coding using ordinary wavelet transform, which has almost the same ROI coding functionalities, SA-ROI outperforms by 5% in lossless compression ratio. Also in lossy coding, except at very low coding rates, SA-ROI has better compression performance.