基于小波尺度相关的图像清晰度判别方法①-计算机系统应用.PDF

计 算 机 系 统 应 用 2010 年 第 19卷 第 8 期 ① 基于小波尺度相关的图像清晰度判别方法 王敏君 熊邦书 黄丽贞 余 亮 (南昌航空大学 无损检测技术教育部重点实验室 江西 南昌 330063) 摘 要： 为提高图像清晰度判别函数的单峰性和抗噪性，提出了一种基于小波变换尺度相关的清晰度判别方法。 该方法利用信号的小波系数幅值随尺度增大而增大，噪声的小波系数幅值随尺度增大而减小的特性， 取相邻尺度间小波系数乘积构造清晰度判别函数，实现了增强信号抑制噪声的目的。通过 CCD 采集 的图像数据对该方法与传统方法进行对比实验，结果表明提出方法具有较好的单峰性和较强的抗噪 性，能够准确地评价数字图像聚焦程度。 关键词： 自动聚焦;图像清晰度;小波变换;尺度相关 Image Definition Evaluation Method Based on Wavelet Scale Correlation WANG Min-Jun, XIONG Bang-Shu, HUANG Li-Zhen ,YU Liang(Key Laboratory of Nondestructive Test of Ministry of Education, Nanchang Hangkong University, Nanchang 330063, China) Abstract ： A novel definition measurement based on correlation of the wavelet transform at adjacent scales is presented, which improves the sharpness function`s performance of unimodality and noise-immunity. It takes advantage of the property that wavelet coefficients magnitude of signals increase as scale increases and wavelet coefficients magnitude of noise decrease with increasing scale and calculates the multiplication of wavelet coefficients at the adjacent scales to construct the evaluation method. It is capable to amplify signals and suppress noise. Compared with traditional algorithms using Image Data acquired by CCD, the proposed method is found to be more robust and accurate to estimate the focusing extent. Keywords: autofocus; image definition; wavelet transform; scale correlation