Imaging Method using Multi-Threshold Pattern for Photon Detection of Quanta Image Sensor

In recent years, the development of the Quanta Image Sensor (QIS), which can observe the amount of incident light intensity in units of photons, has been progressing. In QIS imaging, a large number of photon incident observations are performed in the spatio-temporal direction, and multi-valued images are obtained by reconstruction processing. The observation process outputs a binary value that indicates whether the number of incident photons exceeds a preset threshold number in the minute photon detector (jot). In many existing methods for QIS imaging, a uniform threshold is set for all jots, causing the reconstructed multi-valued image to be overexposed or underexposed. On the other hand, setting an optimal threshold for each local region individually requires time for adjustment, which leads to a decrease in temporal resolution. In this paper, we propose an imaging method that accurately captures a wide range of light intensity by introducing a periodic pattern consisting of multiple thresholds. Since we do not adjust the threshold for each scene individually, we can fundamentally avoid the degradation of temporal resolution. In addition, since the threshold has a variety of values when applied to jots, it is possible to obtain a high-quality multi-valued image even with a small number of photon incident observations. Our proposed method consists of three components that take the characteristics of photon incident observation into account: statistical light intensity estimation, noise reduction, and optimization of the periodic pattern.