Lai Cheung-Ming, Lam Kin-Man, Siu Wan-Chi
Dept. of Electron. and Inf. Eng., Hong Kong Polytech. Univ., China.
IEEE Trans Image Process. 2003;12(11):1398-403. doi: 10.1109/TIP.2003.817246.
A fast algorithm for fractal image coding based on a single kick-out condition and the zero contrast prediction is proposed in this paper. The single kick-out condition can avoid a large number of range-domain block matches when finding the best matched domain block. An efficient method for zero contrast prediction is also proposed, which can determine whether the contrast factor for a domain block is zero or not, and compute the corresponding difference between the range block and the transformed domain block efficiently and exactly. The proposed algorithm can achieve the same reconstructed image quality as the exhaustive search, and can greatly reduce the required computation or runtime. In addition, this algorithm does not need any pre-processing step or additional memory for its implementation, and can combine with other fast fractal algorithms to further improve the speed. Experimental results show that the runtime is reduced by about 50% of that of the exhaustive search method. When combined with the DCT Inner Product algorithm, the required runtime for the algorithm can be further reduced by about 50%. The proposed algorithm was also compared to two other fast fractal algorithms. Experimental results also show that our algorithm achieves a better efficiency and requires a much smaller amount of memory for implementation.
本文提出了一种基于单踢出条件和零对比度预测的分形图像编码快速算法。单踢出条件在寻找最佳匹配域块时可避免大量值域块匹配。还提出了一种有效的零对比度预测方法，该方法可确定域块的对比度因子是否为零，并高效准确地计算值域块与变换后的域块之间的相应差值。所提算法能达到与穷举搜索相同的重建图像质量，且能大幅减少所需计算量或运行时间。此外，该算法实现时无需任何预处理步骤或额外内存，还可与其他快速分形算法结合以进一步提高速度。实验结果表明，运行时间比穷举搜索方法减少了约50%。与离散余弦变换内积算法结合时，该算法所需运行时间可进一步减少约50%。还将所提算法与其他两种快速分形算法进行了比较。实验结果还表明，我们的算法效率更高，实现时所需内存量少得多。
