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Journal of ZheJiang University (Engineering Science)  2021, Vol. 55 Issue (8): 1510-1517    DOI: 10.3785/j.issn.1008-973X.2021.08.012
    
Continuous digital zooming algorithm of dual-focal camera based on texture restoration
Jiong-hui SONG1(),Qi LI1,*(),Jing WANG2,Zhi-hai XU1,Hua-jun FENG1,Yue-ting CHEN1
1. College of Optical Science and Engineering, Zhejiang University, Hangzhou 310027, China
2. Science and Technology on Optical Radiation Laboratory, Beijing 100854, China
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Abstract  

A continuous digital zooming algorithm mainly for dual-focal camera imaging system was proposed. The continuous digital zooming problem of dual-focal camera was divided into the feature transfer problem in the field of view of the long-focus camera and the texture repair problem outside the field of view of the long-focus camera. The texture information of long-focus camera image was used to restore short-focus camera image referring to contextual image restoration algorithm, and a similar network structure was used to reduce the visual difference inside and outside the field of view of the long-focus camera. Experimental results show that compared with other algorithms, the proposed algorithm can improve the quality of images, improve the problem of large gap between the texture details inside and outside the field of view of the long-focus camera, and has higher subjective resolution and better visual clarity. In addition, the algorithm has an obvious repair effect on the texture details outside the field of view of the long-focus camera and also performs well for the actual images.



Key wordsdual-focal camera      continuous digital zooming      context      texture restoration      image restoration     
Received: 03 August 2020      Published: 01 September 2021
CLC:  TP 391  
Fund:  装备预研重点实验室基金资助项目(61424080214);十三五民用航天资助项目
Corresponding Authors: Qi LI     E-mail: 21830051@zju.edu.cn;liqi@zju.edu.cn
Cite this article:

Jiong-hui SONG,Qi LI,Jing WANG,Zhi-hai XU,Hua-jun FENG,Yue-ting CHEN. Continuous digital zooming algorithm of dual-focal camera based on texture restoration. Journal of ZheJiang University (Engineering Science), 2021, 55(8): 1510-1517.

URL:

https://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2021.08.012     OR     https://www.zjujournals.com/eng/Y2021/V55/I8/1510


基于纹理修复的双焦相机连续数字变焦算法

设计主要用于双焦相机成像系统的连续数字变焦算法. 该算法将双焦相机连续数字变焦问题拆分成长焦相机视场内的特征迁移问题和长焦相机视场外的纹理修复问题. 在实现细节上,该算法参考基于上下文语义的图像修复算法的思路,利用长焦相机图像的纹理信息修复短焦相机图像,并在2个问题上使用相似的网络结构来降低长焦相机视场内外细节视觉效果的差异. 实验结果表明,相比其他算法,所提算法能显著提升变焦图像的质量,有效改善长焦相机视场内外纹理细节差距较大的问题,在主客观评价上都具有更好的表现. 此外,该方法对于处于长焦相机视场外的纹理细节,具有明显的修复效果,对于实际拍摄的图像同样有效.


关键词: 双焦相机,  连续数字变焦,  上下文语义,  纹理修复,  图像修复 
Fig.1 Schematic diagram of dual-focus camera imaging system
Fig.2 Flow chart of proposed detail restoration algorithm
Fig.3 Schematic diagram of texture restoration sub-network
Fig.4 Training set images in dataset
Fig.5 Simulation results of continuous digital zoom using different algorithms
Fig.6 Simulation results of different images and different zoom magnifications
算法 ×1.2 ×1.4 ×1.6 ×1.8 ×2.0 ×2.2 ×2.4 ×2.6 ×2.8 ×3.0 ×3.2 ×3.4 ×3.6 ×3.8
双三次插值 35.01 32.93 31.49 30.38 29.55 28.87 28.31 27.89 27.51 27.19 26.89 26.60 26.35 26.07
TTSR[11] 39.79 36.73 34.53 33.27 32.15 31.29 30.56 29.98 29.53 29.19 28.87 28.55 28.29 27.96
文献[9]算法 39.11 36.29 34.05 33.11 32.03 31.07 30.19 29.53 29.02 28.68 28.22 27.89 27.43 27.18
本研究算法 39.46 36.33 34.18 33.25 32.32 31.56 30.89 30.17 29.71 29.43 29.06 28.77 28.50 28.05
Tab.1 PSNR of different zoom magnifications and algorithms
视场 算法 ×1.5 ×2.0 ×2.5 ×3.0 ×3.5
长焦相机视场内 双三次插值 32.03 29.81 28.06 27.12 26.49
TTSR[11] 37.57 34.23 32.04 30.41 29.88
文献[9]算法 36.56 33.44 31.10 29.39 28.53
本研究算法 37.75 34.21 31.93 30.28 29.71
长焦相机视场外 双三次插值 32.25 29.42 27.94 27.26 26.47
TTSR[11] 35.21 31.45 29.08 27.62 27.93
文献[9]算法 34.80 31.54 29.01 27.76 27.31
本研究算法 34.72 31.69 29.58 28.33 28.24
Tab.2 PSNR of inside and outside field of view of long-focal camera
Fig.7 Comparison of texture restoring effects for field out of view of long-focal camera
Fig.8 Comparison of visual effects in transition areas
Fig.9 Experimental result of real images
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