感兴趣区域提升幅度确定及编码

基于小波变换的星载图像压缩中，感兴趣区域编码实现面临主要问题之一是如何确定小波域系数提升的幅度.提出了一种比特平面熵估计值计算模型及计算算法，能够有效逼近比特平面编码实际输出码率，同时提出了系数提升幅度的算法，从而解决了基于比特平面提升的感兴趣区域编码中系数提升幅度确定问题，可以保证感兴趣区域重建质量要求的前提下，背景和总体重建质量更好.该算法是根据图像内容和用户要求计算系数提升幅度，不需要进行人工干预，图像的复杂度不同，提升幅度也会不同.该算法适合感兴趣区域确定如干涉高光谱图像这类图像的编码.仿真结果表明，尽管不同图像具有不同的复杂度，本文算法都能够准确确定感兴趣区域系数的提升幅度，从而有效保证了总体编码效果更好.

Decision of ROI Scaling Value and ROI Coding

In the on-board image coding algorithm, one of the main problems in ROI (Region-of- interest) coding is to decide the scaling value. A novel algorithm for calculating entropy estimate is presented which can approximate to the actual output rate produced by bit-plane coding. Then an algorithm for deciding the scaling value of ROI is proposed by which the scaling value of ROI can be decided correctly. The scaling value is calculated according to the image being coded and the requirement, which does not need inference, with different image complexity different lifted value. So the algorithm in the paper is suitable for those images such as multi-spectral images in which the ROI position is known and their complexity different. The simulation results show that in spite of different complexity the algorithm can decide the lifted value precisely so that the whole reconstructed image quality is better.