A Wavelet Auto-focusing Method of the Aerial Camera Based on CCD Mosaicing

  • 1. College of Resource Environment and Tourism, Capital Normal University, Beijing 100048, China;
    2. Key Laboratory of 3D Information and Acquisition and Application, MOE, Beijing 100048, China;
    3. Beijing Municipal Laboratory of Resources Environment and GIS, Beijing 100048, China;
    4. Key Laboratory of Integrated Disaster Assessment and Risk Governance, MCA, Beijing 100048, China;
    5. School of Astronautic, Harbin Institute of Technology, Harbin 150001, China

Received date: 2011-09-12

  Revised date: 2012-02-02

  Online published: 2012-02-24


A wavelet auto-focusing method is proposed to consider the characteristic of the aerial camera CCD mosaicing structure. In order to evaluate the clarity of the image obtained by the aerial camera, an image assessing function is constructed based on the wavelet transform. The evaluation function is constructed by the wavelet coefficients of the image, and the characteristic of the CCD mosaicing structure was taken use to solve the problem that the evaluating values can't be compared for the variable images. On the basis of the wavelet evaluating function, the quality of the image was assessed. Then the CCD mosaicing structure was utilized to perform auto-focusing process, and a simulation was made to validate the novel method in the end. The weights are set according to the characteristic of the human vision system (HVS). In order to make the function adaptive to different images, the properties of the wavelet basis are analyzed. At the same time, the area with high frequency component is chosen as the evaluating area so as to improve the sensitivity of the evaluating function. And the flow chart of the focusing based on this method is described particularly. There are some innovation in this paper, such as: the weights of the wavelet coefficients in the evaluating function were set according to the characteristic of the wavelet transform and HVS, which is close to human subjective feel and insensitive to noise|the properties of the wavelet basis were analyzed so as to make the function adaptive to images with different high-frequency components|the wavelet basis with the best effect is symlet2 and the level of decomposing is three|the problem that auto-focusing of the aerial camera can't use digital images processing directly was solved by making use of the CCD mosaicing structure. All in all, this paper introduces a wavelet auto-focusing method based on digital image processing to aerial camera used the characteristic of CCD mosaicing structure. The function is close to the HVS subjective feeling and adaptive to objects with different frequency components, and this method is more sensitive and adaptive than traditional wavelet methods. It could obtain high image quality, and is suitable to the application in focusing system of the aerial camera.

Cite this article

LI Shanshan, GONG Huili, LIU Yang, HU Zhuowei . A Wavelet Auto-focusing Method of the Aerial Camera Based on CCD Mosaicing[J]. Journal of Geo-information Science, 2012 , 14(1) : 101 -108,122 . DOI: 10.3724/SP.J.1047.2012.00101


[1] 周成虎,骆剑承.高分辨率卫星遥感影像地学计算[M].北京:科学出版社,2009,11-13.

[2] 赵鹏. 振动对航空相机成像质量影响的分析[J]. 激光与红外,2001,31(4): 240-242.

[3] 徐鹏,黄长宁,王涌天,等. 卫星振动对成像质量影响的仿真分析[J]. 宇航学报,2003,24(3):259-263.

[4] 张洪文.空间相机调焦技术的研究[D].中国科学院长春光学精密机械与物理研究所,2003.

[5] 许兆林,赵育良,刘建东.基于传感器的自动调焦系统设计[J].传感器与微系统,2011,30(4):111-116.

[6] 李开端,李英杰,赵育良,等.基于面阵CCD和小波变换的航空相机自动调焦研究[J].光学技术,2002,28(2):150-154.

[7] 周九飞,翟林培,周刚,等. 航空成像设备自动调焦方法[J]. 光学学报,2010,30(1): 105-108.

[8] 史 磊,金 光,田海英,等.航空相机的自准直自动检焦方法研究[J]. 光学精密工程,2008,16(12) : 2460 -2462.

[9] 鲍歌堂,赵辉,陶卫. 图像测量技术中几种自动调焦算法的对比分析[J]. 上海交通大学学报,2005,39(1): 121-124.

[10] 周贤,姜威.基于图像边缘能量的自动聚焦算法[J].光学技术,2006,32(2):213-218.

[11] Norman B N, Brain H B. Objective Image Quality Measure Derived from Digital Image Power Spectra[J]. Opt.Eng,1992,31(4):813-825.

[12] 王海霞,王昕,徐抒岩,等.功率谱在高分辨率遥感相机检调焦中的应用[J].光学技术,2006,S1:464-467

[13] Widjaja J, Jutamulia S. Wavelet transform-based autofocus camera systems[C]. The 1998 IEEE Asia-Pacific Conference Circuits and Systems on 1998,24-27,49-51.

[14] Cui H, Song G X. Study of the Wavelet Basis Selections[C]. International Conference on Computational Intelligence and Security, 2006,12:1833-1836.

[15] Ma L, Li S N, King N N. Visual Horizontal Effect for Image Quality Assessment[J]. IEEE Signal Processing Letters,2010,17(7):627-630.

[16] 刘先林,段福洲,宫辉力.航空摄影科技发展成就与未来展望[J].前沿科学,2007,3(3):10-14.

[17] 孙杰, 袁跃辉, 王传永. 数字图像处理自动图像聚焦算的的分析和比较[J]. 光学学报, 2007, 27(1): 35-39.

[18] 徐贵力,刘小霞,田裕鹏,等. 一种图像清晰度评价方法[J]. 红外与激光工程,2009,38(1):180-184.

[19] Wang Y,Liu Y,Chen X L. A digital auto-focusing method based on CCD mosaicing for aerial camera[C].The International Symposium on Photoelectronic Detection and Imaging. Beijing, 2011.

[20] 丁亚林,田海英,王家骐.空间遥感相机调焦机构设计[J].光学精密工程,2001,9(2):35-38.