Fully digital auto-focusing system with automatic focusing region selection and point spread function estimation

Jeon, Jaehwan; Yoon, Inhye; Kim, Dong-Gyun; Lee, Jin‐Hee; Paik, Joonki

doi:10.1109/tce.2010.5606247

Cited by 30 publications

(16 citation statements)

References 14 publications

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“…Jeon, et al has proposed an automatic focusing region selection method using entropy in the region of interest in [3].…”

Section: Entropy-based Variable-size Block Partitioningmentioning

confidence: 99%

Moving object segmentation using motion orientation histogram in adaptively partitioned blocks for consumer surveillance system

Lee

Chon³

et al. 2012

2012 IEEE International Conference on Consumer Electronics (ICCE)

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In this paper, we present an efficient moving object segmentation method using motion orientation histogram (MOH) in consideration of variable block-based hardware implementation. In pursuit of both efficiency and reliability, each block motion vector is quantized into one of eight representative orientations. Given a set of motion vectors estimated from regularly divided basic blocks, we adaptively partition the blocks based on entropy for increasing the reliability of estimated motions. We then compute motion orientation histogram (MOH) from appropriately partitioned blocks and quantize them into eight representative orientations. Finally, we decide the object's motion using the quantized orientation of motion and error compensation. Experimental results show that the proposed method can be embedded in an image signal processing (ISP) chip for high-level image processing functions such as object tracking and behavior analysis in consumer surveillance systems.

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“…Jeon, et al has proposed an automatic focusing region selection method using entropy in the region of interest in [3].…”

Section: Entropy-based Variable-size Block Partitioningmentioning

confidence: 99%

Moving object segmentation using motion orientation histogram in adaptively partitioned blocks for consumer surveillance system

Lee

Chon³

et al. 2012

2012 IEEE International Conference on Consumer Electronics (ICCE)

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“…Besides unimodality, a good image quality assessing function should have the following properties: (1) the slope of the assessing curve is not too small in the region with large defocusing amount; (2) there is an obvious peak near the focus location; (3) robustness to different frequency component images and insensitivity to noise [6] [7] . The high-frequency wavelet coefficients at different levels have different contribution to the assessing value and the coefficients of the same level at different direction influence the result differently.…”

Section: Novel Wavelet Estimating Functionmentioning

confidence: 99%

A digital auto-focusing method based on CCD mosaicing for aerial camera

2011

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A novel focusing method of the remote sensing camera is proposed in this paper. To evaluate the quality of the image obtained by the aerial camera, an assessing function was constructed based on the Wavelet transform. And the characteristic of the CCD mosaicing structure was taken use to solve the problem that the evaluating values can not be compared for the images captured by the aerial camera are variable. 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, a simulation was made to validate the novel method in the end. There are three major contributions in the paper. Firstly, the weights of the wavelet coefficients in the evaluating function were set according to the characteristic of the Wavelet transform and human vision system (HVS). By those, the assessing result is close to our subjective feel and insensitive to noise. Secondly, in order to make the function adaptive to images with different high-frequency components, the properties of the wavelet basis were analyzed. By comparing the evaluating effect of different images, the wavelet basis with the best effect is symlet2 and the level of decomposing is three. Finally, by making use of the CCD mosaicing structure, the problem that auto-focusing of the aerial camera can't use digital images processing directly was solved, and the region with the highest frequency component was chosen as the evaluating area so as to improve the sensitivity of the function.

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“…[1][2][3][4][5][6][7][8][9][10] The image-based passive autofocus algorithms are widely studied for their high accuracy and no requirement for extra equipment. [1][2][3][4][5][6][7][8][9][10] The image-based passive autofocus algorithms are widely studied for their high accuracy and no requirement for extra equipment.…”

Section: Introductionmentioning

confidence: 99%

Analysis of image motion on autofocus precision for aerial cameras

et al. 2015

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Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 08/17/2015 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspxAbstract. Aerial cameras often suffer from image motion due to the severe aerial environments that decrease the autofocus precision. An analysis of the influence of image motion on autofocus precision is provided to obtain the optimal focus position. First, the focus measure function based on discrete Fourier transform is applied to evaluate the sharpness of the collected image for autofocusing. Then, two forms of image motion model, including linear shift and jitter, are discussed and analyzed. Finally, a quadratic fitting curve is employed on the focus measure function for image sequence. The maximum of the fitted curve corresponds to the optimal focus position. Experimental results demonstrate that the maximum value of the focus measure function decreases more than 10% approximately when the image motion increases to five pixels, and the optimal focus position computed by quadratic fitted curve generated a good performance in autofocus techniques. The proposed autofocus algorithm can be applied to aerial cameras.

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Fully digital auto-focusing system with automatic focusing region selection and point spread function estimation

Cited by 30 publications

References 14 publications

Moving object segmentation using motion orientation histogram in adaptively partitioned blocks for consumer surveillance system

Moving object segmentation using motion orientation histogram in adaptively partitioned blocks for consumer surveillance system

A digital auto-focusing method based on CCD mosaicing for aerial camera

Analysis of image motion on autofocus precision for aerial cameras

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