Random on-board pixel sampling (ROPS) X-ray Camera

TL;DR

This paper explores the use of compressed sensing and random on-board pixel sampling (ROPS) to enable high-speed, efficient X-ray imaging, especially for sparse or redundant data, through novel circuit architectures and computational techniques.

Contribution

It introduces the concept of ROPS for X-ray cameras, demonstrating its feasibility and proposing a multilayer circuit architecture for random pixel access and in-pixel storage.

Findings

Feasibility of ROPS demonstrated with existing X-ray images

Discussion of signal-to-noise ratio as a function of pixel size

Proposed multilayer architecture for random pixel access

Abstract

Recent advances in compressed sensing theory and algorithms offer new possibilities for high-speed X-ray camera design. In many CMOS cameras, each pixel has an independent on-board circuit that includes an amplifier, noise rejection, signal shaper, an analog-to-digital converter (ADC), and optional in-pixel storage. When X-ray images are sparse, i.e., when one of the following cases is true: (a.) The number of pixels with true X-ray hits is much smaller than the total number of pixels; (b.) The X-ray information is redundant; or (c.) Some prior knowledge about the X-ray images exists, sparse sampling may be allowed. Here we first illustrate the feasibility of random on-board pixel sampling (ROPS) using an existing set of X-ray images, followed by a discussion about signal to noise as a function of pixel size. Next, we describe a possible circuit architecture to achieve random pixel access and in-pixel storage. The combination of a multilayer architecture, sparse on-chip sampling, and computational image techniques, is expected to facilitate the development and applications of high-speed X-ray camera technology.