# A Noise-aware Enhancement Method for Underexposed Images

## TL;DR

This paper introduces a noise-aware contrast enhancement technique for underexposed images that improves dark region visibility while suppressing noise amplification, addressing limitations of existing methods.

## Contribution

It proposes a novel contrast enhancement method combining adaptive gamma correction with a shadow-up function and denoising filter to preserve details and reduce noise.

## Key findings

- Enhanced contrast in dark regions without noise amplification
- Effective in strong noise environments
- Preserves details in bright regions

## Abstract

A novel method of contrast enhancement is proposed for underexposed images, in which heavy noise is hidden. Under low light conditions, images taken by digital cameras have low contrast in dark or bright regions. This is due to a limited dynamic range that imaging sensors have. For these reasons, various contrast enhancement methods have been proposed so far. These methods, however, have two problems: (1) The loss of details in bright regions due to over-enhancement of contrast. (2) The noise is amplified in dark regions because conventional enhancement methods do not consider noise included in images. The proposed method aims to overcome these problems. In the proposed method, a shadow-up function is applied to adaptive gamma correction with weighting distribution, and a denoising filter is also used to avoid noise being amplified in dark regions. As a result, the proposed method allows us not only to enhance contrast of dark regions, but also to avoid amplifying noise, even under strong noise environments.