印刷品水印图像的半色调算法比较

对Bayer抖动、误差扩散和绿噪声3种半色调算法进行了分析比较。利用离散小波变换将水印信息嵌入宿主图像,采用峰值信噪比对3种算法生成的半色调图像质量进行客观评价;用归一化相关系数衡量半色调图像提取的水印质量;以Matlab程序运行时间判断3种算法的计算效率;同时,结合人眼视觉对半色调图像质量进行主观评价。综合各种评价,结果表明:误差扩散是最适合小波水印图像的半色调算法。

Comparison Study of Halftoning Algorithm for Printed Watermarking Image

With the aim of finding the appropriate halftoning algorithms for watermarking of the printed image, three commonly used types of halftoning algorithm i.e. Bayer dithering, error diffusion and green noise are compared. The watermark information is embedded in the host image using discrete wavelet transform. PSNR is used to evaluate the quality of halftone images generated by the three algorithms, NC to measure the quality of extracted watermark, and the running time of halftoning to determine the computational complexity. Combined with human visual subjective, the comprehensive evaluation has been presented for the halftone image. The experimental results show that error diffusion has the best performance for wavelet watermark image.