Double Binnable RGB, RGBW and LMS Color Filter Arrays

TL;DR

This paper introduces novel double binnable RGBW and LMS color filter arrays for CMOS sensors, improving demosaicking quality and low-light performance over existing Bayer patterns through spectral degeneracy avoidance and efficient binning.

Contribution

It presents new double binnable RGBW and LMS CFAs that outperform traditional Bayer patterns in demosaicking and low-light conditions, addressing spectral degeneracies.

Findings

RGBW offers a 6 dB SNR advantage in low-light conditions.

Hexadeca Bayer can outperform Quad Bayer in demosaicking quality.

New CFAs are free from spectral degeneracies and suitable for full resolution and binned modes.

Abstract

New, high-resolution CMOS image sensors for mobile phones have moved beyond the single-binnable Quad Bayer and RGBW-Kodak patterns to the double binnable Hexadeca Bayer pattern featuring 4x4 tiles of like-colored pixels. Pixel binning enables high-speed, low-power readout in low-resolution modes and, more importantly, a reduction of read noise via floating diffusion binning. In this paper, we present the non-intuitive result that Nona and Hexadeca Bayer can be superior to Quad Bayer in demosaicking quality due to degeneracies in the latter's spectrum. However, Hexadeca Bayer suffers from the weakness of generating Quad Bayer after on round of binning. We introduce novel double binnable RGBW and LMS CFAs, composed of 2x2 tiles capable of 4:1 floating diffusion binning, that are free from spectral degeneracies and thus demosaic well in full resolution and both binned modes. RGBW offers a 6 dB low-light, read noise-limited, SNR advantage over Quad and Hexadeca Bayer in all resolution modes, while for LMS, the corresponding advantage is 4.2 dB.