摘要
通过对双向混合差分方法以及3-参数变长编码方法的研究与分析,针对数字图像编码提出了一种多向混合差分预处理方法。多向混合差分方法先根据当前点的邻近4点对当前点作局部特征分析,然后根据分析结果在基本差分方向中选择当前点的最佳差分方向。相对于双向混合差分方法,多向混合差分方法无需保存方向标志位;基本差分方向进一步细分为4种方向。与双向混合差分的实验结果相比,经多向混合差分处理后的测试图像平均熵值降低了8.2%,编码后单个像素值所占平均比特数降低了11%。实验结果表明,该方法可以把数字图像的熵值降到一个较低的水平,从而有利于编码效率的提高。
In view of the digital image coding, the authors proposed a muhi-directional hybrid differential method based on the analysis of two-directional hybrid differential and 3-parameter variable length coding method. Firstly, multi-directional hybrid differential method was used to analyze local feature of the current pixel based on other four pixels nearby. Then according to the analysis results, an optimal differential direction for the current pixel was chosen from several primary differential directions. Compared with two-directional hybrid differential, multi-directional hybrid differential did not save direction flags. Primary directions contained four differential directions. Compared with results of two-directional hybrid differential, the entropy value of image processed by multi-direction hybrid differential was reduced by 8.2% and the bits per pixel was reduced by 11%. The experimental results show that this algorithm is useful for improving the coding efficiency by reducing the entropy value of digital image to a lower level.
出处
《计算机应用》
CSCD
北大核心
2015年第9期2648-2651,共4页
journal of Computer Applications
关键词
数字图像预处理
数据提取
混合差分
3-参数变长编码
游程编码
digital image pre-processing
data extraction
hybrid differential
3-parameter variable length coding
run-length coding
