Megapixel Photon-Counting Color Imaging using Quanta Image Sensor
This enables color imaging in extremely low-light scenarios, addressing a bottleneck for applications like night vision or scientific imaging, though it is incremental as it builds on existing monochrome QIS technology.
The paper tackled the challenge of passive color imaging with single-photon detectors by presenting the first color Quanta Image Sensor with 1024x1024 resolution, achieving superior performance in very low-light conditions with mean exposures as low as a few photons per pixel.
Quanta Image Sensor (QIS) is a single-photon detector designed for extremely low light imaging conditions. Majority of the existing QIS prototypes are monochrome based on single-photon avalanche diodes (SPAD). Passive color imaging has not been demonstrated with single-photon detectors due to the intrinsic difficulty of shrinking the pixel size and increasing the spatial resolution while maintaining acceptable intra-pixel cross-talk. In this paper, we present image reconstruction of the first color QIS with a resolution of $1024 \times 1024$ pixels, supporting both single-bit and multi-bit photon counting capability. Our color image reconstruction is enabled by a customized joint demosaicing-denoising algorithm, leveraging truncated Poisson statistics and variance stabilizing transforms. Experimental results of the new sensor and algorithm demonstrate superior color imaging performance for very low-light conditions with a mean exposure of as low as a few photons per pixel in both real and simulated images.