High dynamic range colour imaging using complementary metal-oxide-semiconductor (CMOS) sensors with non-destructive readout

Abstract

We present a novel colour reconstruction approach for a high dynamic range camera based on a CMOS sensor with non-destructive readout. The output of such a sensor consists of a sequence of noisy mosaic images that can be combined to create a colour image having a high dynamic range. We show that intuitive sequential processing, where dynamic range enhancement is followed by conventional demosaicing, is prone to introduce extra errors due to ‘stepped gradient’ artefacts and residual system noise. We propose an alternative joint reconstruction algorithm that utilizes all available data to improve the quality of the resulting full colour image. Conventional colour reconstruction quality evaluation, camera noise tests and visual observations show that the proposed method does not produce ‘stepped gradient’ artefacts and generally outperforms a sequential approach based on traditional demosaicing routines for a wide range of system noise values. It also provides a steady increase in dynamic range when the number of non-destructive samples grows.