变焦跟踪曲线在对焦中的应用  

Application of zoom tracking curves in focusing

作　　者：罗钧[1] 孙力[1] 闵志盛[1] 

机构地区：[1]重庆大学光电技术及系统教育部重点实验室,重庆400030

出　　处：《光学精密工程》2011年第10期2326-2332,共7页Optics and Precision Engineering

基　　金：国防科工委国防军工计量"十一五"计划重点项目(No.B20301118);重庆市信息产业局科技攻关基金资助项目(No.200113013)

摘　　要：在变焦成像系统中,及时准确地获取跟踪曲线是变焦跟踪的关键,因此,本文提出了一种计算变焦跟踪曲线的策略。首先,采用基于RAW格式图像的梯度算子计算实时图像清晰度;然后,拟合记录的变焦电机和对焦电机的位置关系,得到远物距端和近物距端的两条跟踪曲线,构成变焦跟踪曲线的上下边界;最后,结合几何法和自适应法,应用获取的变焦跟踪曲线上下边界,计算得到系统所处物距下的跟踪曲线。在自主开发的变焦成像系统中采用梯度算子获取了变焦曲线的上下边界,并通过上述策略实现了变焦跟踪,得到了变焦过程中的图像。实验结果表明,使用所述算法的变焦成像系统其图像清晰度比只用自动对焦算法提高了30%以上;将变焦跟踪曲线应用在对焦中,能够提高变焦过程的图像对焦质量。It is most critical to acquire exact trace curves in time for realizing the zoom tracking in zoom imaging systems.Therefore,a novel computation strategy for zoom tracking curves is proposed.First,a real-time in-focus point is computed by using an image sharpness evaluation operator based on RAW format.Then,the position relations between zoom motor and focus motor are fitted to acquire the two trace curves at the near end and far end of object distances,which are regarded as the upper and lower bounds of trace curves.Finally,both geometric and adaptive zoom tracking methods are combined to be a hybrid algorithm to acquire the curves at some object distances by the method of interpolation.The trace curves for upper and lower bounds are obtained by a gradient operator on a self-developed zoom imaging system,zoom tracking is implemented with acquired trace curves and the image during zoom tracing is acquired.The obtained results show that the image quality of imaging system using proposed approach is improved by 30% as compared with that of the traditional system.It demonstrates that zoom tracking curves can be applied in focusing,and the image quality is improved during zoom tracing.

关 键 词：变焦系统 跟踪曲线 变焦跟踪 

分 类 号：TB853.1[一般工业技术—摄影技术]