CCD视频幅值调节器的设计及目标精确定位算法

Design of CCD video amplitude controller and target precise locating algorithm

针对具有不同亮度的点目标或某点目标亮度不断变化的情形,设计了线阵CCD视频幅值调节器反馈系统。应用固定双阈值法进行边界检测并利用灰度重心法进行像元细分,以实现对点目标的精确定位。CCD视频幅值调节器控制系统通过对光积分时间和程控增益的定量数控调节,使每线视频信号的光点图像目标的尖峰灰度幅值保持恒定,显著降低了对光源和光路的设计难度和成本。固定双阈值边界检测定位法可以截取品质很好的对称边缘,避免了光点尖部不规则对定位结果的影响。与传统的二值化方法相比,该系统不需要额外的二值化参考电平硬件电路,系统简单可靠,算法优越,可以实现<1/10 pixel的细分效果,定位结果保留小数点后2位有效数字,在工程应用上实现了对光点的精确定位,其2变量无级调光数控系统方案可为多变量摄像调光系统的设计提供重要参考。

Aiming at the circumstances of time varying target brightness or multiple targets with different brightnesses,a video amplitude controller feedback system is designed to precisely locate a spot target image on a linear CCD with edge detection by fixed dual thresholds and pixel subdivision by gray weighted centroid algorithm. By adjusting quantitively in tegrating time and program controlling gain,this light adjusting control loop can be kept a constant peak gray value to reduce design difficults for light source and light path and to reduce design cost also. A fixed dual-threshold edge location method is used to truncate a good edge symmetry to aviod the effect of irregularity of the spot peak on location results. Compared with the traditional binarization method with extra external circuits, this system shows its advantages in simple implementation and excellent algorithm, and engineering application gives that it can precisely locate a light spot. Under such circumstance,gray weighted centroid algorithm can reach a better than 1/10 pixel subdivision,so the final spot precise location keeps 2 significant digits after decimal point. Experimental results show that proposed system scheme provides an valuable reference for the future design of multiple-varible light adjusting video system applied in optoeletctronic measurement.