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Alternative TitleA Study of Image Quality Assessment for Ringing Artifacts Based on Contourlet
Thesis Advisor彭思龙
Degree Grantor中国科学院大学
Place of Conferral中国科学院自动化研究所
Degree Discipline计算机技术
Keyword图像质量评价 振铃效应 Contourlet变换 频率域相对误差 Image Quality Assessment Ringing Artifacts Contourlet Transform Relative Error In Frequency domaIn
Abstract图像是人类感知世界和沟通交流的重要信息方式,其质量关系到获取信息的充分性和准确性。然而图像在获取、存储、传输、重建等过程中有质量下降问题,因此评价图像质量就有很重要的作用,能够有效地用于图像处理的各个环节,作为预处理或结果分析。 由于人是图像的最终接受者,所以主观的图像评价方法才是目前最准确的评价方式,因此主观评价方法的结果也用于评判客观评价方法的性能。但是主观评价算法受到很多条件制约,如实验环境的影响、显示设备的不同以及实验者心理情绪的变化等,同时主观方法非常耗时且需要大量专业的参与者,难以自动化地进行质量评价。图像质量评价算法一般要嵌入图像处理系统中,以对图像进行预处理。但主观评价算法无法实现在线作业,所以现在研究的重点是客观评价方法。 本文在分析图像去模糊后产生的振铃效应及Contourlet变换的多尺度和多方向特性的基础上,结合频率域相对误差对不同程度振铃效应的区分特性,提出了基于Contourlet变换的图像质量评价算法,得到更符合人眼视觉特性的评价结果。该算法首先将原始图像和失真图像进行三层Contourlet变换,然后在各层频带上进行误差计算,最后根据各层频带误差统计量与主观评分的相关系数加权融合,得到整体的客观图像质量评价指标。通过上述处理可以获得和观测者的主观感受相一致的评价结果。实验表明,这种方法评价比峰值信噪比等图像质量评估指标更接近人类主观感受。
Other AbstractImage is an important way of perceiving information and communicating. Image quality is closely related to the adequacy and accuracy of the obtained information. However, images have the problem of quality decreasing during acquisition, storage, transmission and reconstruction process. So image quality assessment would play an important role across the chain of image processing, as preprocessing or result analysis. For human being is the ultimate receiver of the image, the subjective method is the most accurate way of evaluation. The results of the subjective evaluation method are also used for assessing the performance of the objective evaluation method. But the subjective evaluation method is conditioned by factors such as the experimental environment, display equipment and the psychological emotion experimenters. The subjective method is very time-consuming and requires a lot of professional players, difficult to be automatic. Image quality assessment algorithm is generally embedded in image processing system, as part of the image preprocessing. But the subjective evaluation method cannot realize online working, so the focus of the study is the objective evaluation method. In this paper, the ringing artifacts produced during image deblurring and the multi-scale and multi-direction characteristics of the Contourlet transform are analyzed. Combined with the characteristics of relative error in frequency domain to distinguish the ringing artifacts, an image quality assessment algorithm based on Contourlet transform is proposed. Firstly, the original image and the distorted image are decomposed to three levels by Contourlet transform. Then the error in each layer is calculated. Finally, weighted by the correlation coefficient between the error statistics in each layer and subjective score, the index of overall image quality is computed. Through the above algorithm, we can get the evaluation results consistent with the observer's subjective feelings. Experiments show that, this method is closer to human perception than other algorithms like the Peak Signal-to-Noise Ratio.
Other Identifier2012E8014661097
Document Type学位论文
Recommended Citation
GB/T 7714
王亚运. 基于Contourlet的振铃效应图像质量评价方法研究[D]. 中国科学院自动化研究所. 中国科学院大学,2015.
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