Abstract

High dynamic range (HDR) images give a strong disposition to capture all parts of natural scene information due to their wider brightness range than traditional low dynamic range (LDR) images. However, to visualize HDR images on common LDR displays, tone mapping operations (TMOs) are extra required, which inevitably lead to visual quality degradation, especially in the bright and dark regions. To evaluate the performance of different TMOs accurately, this paper proposes a blind tone-mapped image quality assessment method based on regional sparse response and aesthetics (RSRA-BTMI) by considering the influences of detail information and color on the human visual system. Specifically, for the detail loss in a tone-mapped image (TMI), multi-dictionaries are first designed for different brightness regions and whole TMI. Then regional sparse atoms aggregated by local entropy and global reconstruction residuals are presented to characterize the regional and global detail distortion in TMI, respectively. Besides, a few efficient aesthetic features are extracted to measure the color unnaturalness of TMI. Finally, all extracted features are linked with relevant subjective scores to conduct quality regression via random forest. Experimental results on the ESPL-LIVE HDR database demonstrate that the proposed RSRA-BTMI method is superior to the existing state-of-the-art blind TMI quality assessment methods.

Highlights

  • High dynamic range (HDR) imaging, as a popular image enhancement technology, aims at recovering the detail information in bright and dark regions of images by fusing multiple low dynamic range (LDR) images with varying exposure levels [1]

  • The images processed by tone-mapping operators (TMOs) and their corresponding subjective scores were utilized in the experiment

  • A blind tone-mapped image quality assessment method based on regional sparse response and aesthetics (RSRA-BTMI) was proposed by designing novel local and global feature subsets

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Summary

Introduction

High dynamic range (HDR) imaging, as a popular image enhancement technology, aims at recovering the detail information in bright and dark regions of images by fusing multiple low dynamic range (LDR) images with varying exposure levels [1]. HDR images have a powerful ability to acquire almost all brightness ranges in natural scenes, and have attracted attention from various multimedia signal processing fields, such as HDR compression, streaming and display [2]. Due to the limitations on popularization of HDR display devices, tone-mapping operators (TMOs) have been successively developed to ensure the visualization of HDR images on traditional. There are no completely suitable TMOs for converting HDR images, so that the relevant visual quality degradation phenomena (e.g., detail loss especially in the bright and dark regions and color unnaturalness) will be inevitably introduced into tone-mapped images (TMIs) [4]. To distinguish the generalization ability of different TMOs accurately, objective image quality assessment (IQA) of TMIs is one of the most challenging problems to optimize the HDR processing pipeline.

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