Device and algorithms for camera timing evaluation

摘要

This paper presents a novel device and algorithms for measuring the different timings of digital cameras shooting both still images and videos. These timings include exposure (or shutter) time, electronic rolling shutter (ERS), frame rate, vertical blanking, time lags, missing frames, and duplicated frames. The device, the DxO LED Universal Timer (or "timer"), is designed to allow remotely-controlled automated timing measurements using five synchronized lines of one hundred LEDs each to provide accurate results; each line can be independently controlled if needed. The device meets the requirements of ISO 15781. Camera timings are measured by automatically counting the number of lit LEDs on each line in still and video images of the device and finding the positions of the LEDs within a single frame or between different frames. Measurement algorithms are completely automated: positional markers on the device facilitate automatic detection of the timer as well as the positions of lit LEDs in the images. No manual computation or positioning is required. We used this system to measure the timings of several smartphones under different lighting and setting parameters.