Journal of Computer Applications ›› 2016, Vol. 36 ›› Issue (7): 1927-1932.DOI: 10.11772/j.issn.1001-9081.2016.07.1927

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Quaternion wavelet transform for evaluation of image sharpness

WANG Zhiwen1, LUO Xiaoqing1, ZHANG Zhancheng2   

  1. 1. School of Internet of Things, Jiangnan University, Wuxi Jiangsu 214122, China;
    2. College of Electronic and Information Engineering, Suzhou University of Science and Technology, Suzhou Jiangsu 215009, China
  • Received:2015-12-14 Revised:2016-03-29 Online:2016-07-10 Published:2016-07-14
  • Supported by:
    This work is partially supported by the National Natural Science Foundation of China (61373055), the Natural Science Foundation of Jiangsu Province(Bk20151358, Bk20151202, jh10-28), Approved Project of Ministry of Housing and Urban-Rural Construction of China (2015-k8-035), the Fundamental Research Funds for the Central Universities (JUSRP51618B).

基于四元数小波变换的清晰度评价

王治文1, 罗晓清1, 张战成2   

  1. 1. 江南大学 物联网工程学院, 江苏 无锡 214122;
    2. 苏州科技学院 电子与信息工程学院, 江苏 苏州 215009
  • 通讯作者: 罗晓清
  • 作者简介:王治文(1992-),男,湖北荆州人,硕士研究生,主要研究方向:图像处理;罗晓清(1980-),女,江西南昌人,副教授,博士,主要研究方向:模式识别、图像处理;张战成(1977-),男,山西平遥人,副教授,博士,主要研究方向:模式识别、图像处理。
  • 基金资助:
    国家自然科学基金资助项目(61373055);江苏省自然科学基金资助项目(Bk20151358,Bk20151202,jh10-28);住房和城乡建设部批准项目(2015-k8-035);中央高校基本科研业务费专项资金资助项目(JUSRP51618B)。

Abstract: The current image sharpness evaluation methods suffer from insufficient discrimination and monotonicity as well as the narrow applicable scope in the process of measurement. In order to solve the problems, an image sharpness evaluation method based on amplitude and phase of Quaternion Wavelet Transform (QWT) was proposed. The image was transformed into frequency domain from spatial domain by QWT, the amplitude and phase information of low frequency subband and high frequency subbands were got by further calculation of the QWT coefficients. After multiplication of the gradient of amplitude and corresponding directional phase, the proposed sharpness metrics were obtained by adding each direction's value together. The proposed sharpness metrics were conducted on the images with different content, degree of blur and degree of noise. Compared with the existing algorithms, the proposed algorithm has a fine monotonicity and discrimination for all kinds of images. The experimental results show that the proposed sharpness metrics not only overcome the shortcomings of the existing algorithms in the monotonicity and discrimination, but also can be applied to image processing.

Key words: image processing, sharpness evaluation, Quaternion Wavelet Transform (QWT), amplitude, phase, gradient

摘要: 针对当前各种图像清晰度评价方法在清晰度判别过程中单调性和区分度不够以及适用范围较小的问题,提出了一种基于四元数小波变换(QWT)幅值与相位的图像清晰度评价方法。该算法通过四元数小波变换将图像从空间域变换到频率域,对得到的四元数小波变换系数进一步计算之后获得低频子带与高频子带的幅值与相位信息,求得低频子带幅值各方向的梯度之后与对应方向的相位相乘求和,最终得到两个清晰度指标值。采用该算法与多种现有算法对不同内容的图像、不同程度模糊的图像以及含有不同程度噪声的图像进行清晰度评价实验:相对于现有算法,所提算法在对上述多种图像的清晰度评价中都保持着很好的单调性与区分度。实验结果表明,所提算法不但克服了现有算法在单调性与区分度上的不足,而且所提清晰度评价指标可以应用在图像处理中。

关键词: 图像处理, 清晰度评价, 四元数小波变换, 幅值, 相位, 梯度

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