In this paper, we review the LED flicker metrics as defined by the IEEE P2020 working group. The goal of these metrics is to quantify the flicker behaviour of a camera system, to enable engineers to quantify flicker mitigation, and to identify and explore challenging flicker use cases and system limitations. In brief, Flicker Modulation Index quantifies the modulation of a flickering light source, and is particularly useful for quantifying banding effects in rolling shutter cameras. Flicker Detection Index quantifies the ability of a camera system to distinguish a flickering light source from the background signal level. Modulation Mitigation Probably quantifies the ability of a camera system to mitigate modulation of a flickering light source. This paper explores various use cases of flicker, how the IEEE P2020 metrics can be used to quantify camera system performance in these use cases, and discusses measurement and reporting considerations for lab based flicker assessment.
In recent years, the use of LED lighting has become widespread in the automotive environment, largely because of their high energy efficiency, reliability, and low maintenance costs. There has also been a concurrent increase in the use and complexity of automotive camera systems. To a large extent, LED lighting and automotive camera technology evolved separately and independently. As the use of both technologies has increased, it has become clear that LED lighting poses significant challenges for automotive imaging i.e. so-called "LED flicker". LED flicker is an artifact observed in digital imaging where an imaged light source appears to flicker, even though the light source appears constant to a human observer. This paper defines the root cause and manifestations of LED flicker. It defines the use cases where LED flicker occurs, and related consequences. It further defines a test methodology and metrics for evaluating an imaging systems susceptibility to LED flicker.