脉冲连续摄影原理与超高速高动态成像验证  

Spiking Continuous Photographing Principle and Demonstration on Ultrahigh Speed and High Dynamic Imaging

作　　者：黄铁军[1] HUANG Tie-jun(School of Computer Science,State Key Laboratory of Multimedia Information Processing,Peking University,Beijing 100871,China)

机构地区：[1]北京大学计算机学院多媒体信息处理全国重点实验室,北京100871

出　　处：《电子学报》2022年第12期2919-2927,共9页Acta Electronica Sinica

基　　金：国家自然科学基金(No.61425025)。

摘　　要：传统相机采用定时曝光方式获得静态图像或图像序列形式的视频,不能有效表达极高速的光子流过程,而且导致高速和高动态相互对立的“两难困境”.基于光电传感器像素独立的特点,提出了连续摄影原理:每个像素各自把接收的光子流转换成电子流,连续测量光电流并转换成数字信息流,实现像素级别的连续表达,再按照像素空间排布组成序列阵列,就是对像素平面入射光子流过程的连续表达.截取序列阵列任何一个时刻的状态就可得到该时刻的图像,从而实现连续成像.进而,提出了把光电子流调制为脉冲序列的脉冲连续摄影原理:像素从清空状态开始积累电荷,达到额定阈值时产生一个脉冲作为积满标志并自动复位重新开始累积,如此重复.一个脉冲积满所经历的时间称为它的脉宽,与这个时段的光强成反比,据此可以估计这一时段的光强.脉冲按照自然时序排列而成的脉冲序列就是对光电子流过程的数字化表达.各像素产生的脉冲流按照像素空间分布排列而成的脉冲流阵列称为视象,蕴含了光过程丰富的时空信息,从中可以生成任意时刻的图像,实现超高速、高动态、无模糊连续成像,解决了定时曝光成像的“两难困境”.脉冲连续摄影原理的唯一参数是累积阈值Q,对应积满一个脉冲所需光子/电子数,唯一变量是脉冲累积时长τ,是最容易准确测量的物理量,并可以利用自然时序简练表达.任意时刻的光强为Q/τ,由所处脉冲的宽度τ决定,τ的取值范围是(0,∞),因此理论上可以表达任意强度的光,动态范围无穷大.实际物理实现中,强光表达的极限取决于电路最短读出时间,暗光表达极限就是暗电流强度,它累积为一个脉冲的时长■即相机的动态范围,采用常规光电器件和电路就能实现160 dB甚至180 dB超高动态成像.在要求成像时间灵敏度小于■时,可通过对累积电压亚阈值�Traditional camera accumulates photons during an exposure time window to generate a still image or a video in the form of image sequences, which lose the temporal process of the photons flow, leads to an irreconcilable dilemma between high-dynamic and high-speed imaging. Based on the fact that the pixels of the photoelectric sensor are independent, a new continuous photographing principle is proposed: each pixel converts the received photon flow into an electronic flow independently, continuously measures the photoelectric current and converts it into a digital flow, and represents continuously at the pixel level. Then the sequence array ranked according to the pixel layout is a continuous representation of the photons shotting on the sensing plane. The image of any moment can be obtained by intercepting the state of the sequence array, so as to realize continuous imaging.Furthermore, the spiking continuous photographing principle that modulates the photon flow into a spike sequence is proposed: for each pixel, accumulate charge from the reset state, generate a spike as a flag once the specified threshold is reached,reset and repeat. The duration that a spike takes to be fired is called its spiking width, which is inversely proportional to the light intensity during this period. Based on this, the light intensity during this period can be estimated. The spikes sequence with natural temporal order is a digital representation of the photon flow process. The array of the spike sequences according to the spatial layout of pixels is called “viform”, which contains rich spatial and temporal information of the light process. An image at any moment can be calculated from viform, thereby ultrahigh-speed, high-dynamic and non-blurred continuous imaging is achieved, and the dilemma between high-dynamic and high-speed imaging of exposure imaging is solved completely.The unique parameter of the spiking continuous photographing principle is the accumulation threshold Q, which corresponds to the number of photons/electrons

关 键 词：光电传感器 脉冲序列调制 连续摄影 高动态成像 超高速成像 相机 视象 

分 类 号：TB8[一般工业技术—摄影技术] TP391[自动化与计算机技术—计算机应用技术]