# Learning a No-Reference Quality Assessment Model of Enhanced Images With Big Data

## TL;DR

This paper introduces a new no-reference image quality assessment model trained on large datasets, which effectively guides image enhancement processes to improve various types of images, outperforming existing methods.

## Contribution

Developed a novel no-reference IQA model using big data for feature extraction and regression, and established a robust image enhancement framework guided by this IQA measure.

## Key findings

- The proposed IQA model outperforms state-of-the-art methods on nine datasets.
- The enhancement framework effectively improves natural, low-contrast, low-light, and dehazed images.
- The method demonstrates high efficiency and robustness in image quality assessment and enhancement.

## Abstract

In this paper we investigate into the problem of image quality assessment (IQA) and enhancement via machine learning. This issue has long attracted a wide range of attention in computational intelligence and image processing communities, since, for many practical applications, e.g. object detection and recognition, raw images are usually needed to be appropriately enhanced to raise the visual quality (e.g. visibility and contrast). In fact, proper enhancement can noticeably improve the quality of input images, even better than originally captured images which are generally thought to be of the best quality. In this work, we present two most important contributions. The first contribution is to develop a new no-reference (NR) IQA model. Given an image, our quality measure first extracts 17 features through analysis of contrast, sharpness, brightness and more, and then yields a measre of visual quality using a regression module, which is learned with big-data training samples that are much bigger than the size of relevant image datasets. Results of experiments on nine datasets validate the superiority and efficiency of our blind metric compared with typical state-of-the-art full-, reduced- and no-reference IQA methods. The second contribution is that a robust image enhancement framework is established based on quality optimization. For an input image, by the guidance of the proposed NR-IQA measure, we conduct histogram modification to successively rectify image brightness and contrast to a proper level. Thorough tests demonstrate that our framework can well enhance natural images, low-contrast images, low-light images and dehazed images. The source code will be released at https://sites.google.com/site/guke198701/publications.