In-Pixel Foreground and Contrast Enhancement Circuits with Customizable Mapping

TL;DR

This paper introduces a customizable in-pixel contrast enhancement circuit capable of real-time foreground suppression and contrast improvement, significantly enhancing image quality directly within the pixel array.

Contribution

It presents a novel in-pixel circuit design that performs adaptive contrast enhancement and foreground suppression, tunable during design and operation.

Findings

6x increase in Michelson Contrast Ratio in simulations

Effective foreground suppression in low-light conditions

Adaptive contrast enhancement demonstrated in pixel array

Abstract

This paper presents an innovative in-pixel contrast enhancement circuit that performs image processing directly within the pixel circuit. The circuit can be tuned for different modes of operation. In foreground enhancement mode, it suppresses low-intensity background pixels to nearly zero, isolating the foreground for better object visibility. In contrast enhancement mode, it improves overall image contrast. The contrast enhancement function is customizable both during the design phase and in real-time, allowing the circuit to adapt to specific applications and varying lighting conditions. A model of the designed pixel circuit is developed and applied to a full pixel array, demonstrating significant improvements in image quality. Simulations performed in HSPICE show a nearly 6x increase in Michelson Contrast Ratio (CR) in the foreground enhancement mode. The simulation results indicate its potential for real-time, adaptive contrast enhancement across various imaging environments.