Contrast Enhancement Evaluation Database (CEED2016)

The CEED2016 is newly developed image database dedicated to contrast enhancement evaluation. The database contains 30 original color images and 180 enhanced images obtained using six different CE methods. The database is built with our own captured images and some common pictures used by the image processing community. The subjective experiments were performed at Universite Paris 13, Sorbonne Paris Cité at Laboratoire de Traitement et Transport de l’Information (L2TI). The images were displayed on a calibrated LCD monitor in a dark room environment to avoid any problem with the illumination adaptation of background. Twenty-three observers, 10 experts, and 13 non-experts, from different age groups, gender, and background participated in the experiments. To obtain the ranking scores, we adopted a balanced pairwise preference based ranking protocol. The interface for the subjective experiments was developed in Matlab, where, for each original image, we randomly displayed all possible pair combinations of enhanced images to the observers. We also showed the original image in the center of the screen (a pair of enhanced images are displayed to its left and right), to facilitate the analysis of after effects of CE. The observers had the choice to rank equally similar stimuli. In the PC ranking protocol, each enhanced image is compared with the others in pairs and ranking results are stored in a preference matrix.CEED2016是专为对比度增强（Contrast Enhancement, CE）评估开发的新型图像数据库。该数据库包含30幅原始彩色图像，以及通过6种不同对比度增强方法生成的180幅增强图像。数据库素材既涵盖自主拍摄的图像，也包含图像处理领域常用的部分通用图片。主观实验在巴黎索邦巴黎西岱大学巴黎第十三大学的信息处理与传输实验室（Laboratoire de Traitement et Transport de l’Information, L2TI）开展。实验在暗室环境中通过经过校准的LCD显示器展示图像，以规避背景光照适配带来的干扰。来自不同年龄层、性别与背景的23名观察者参与了本次实验，其中包括10名领域专家与13名非专家。为获取图像排序评分，我们采用了基于均衡成对偏好的排序协议。主观实验的交互界面基于Matlab开发：针对每幅原始图像，系统会随机将所有增强图像的成对组合展示给观察者；同时将原始图像显示于屏幕中央，成对的增强图像分别展示于其左右两侧，以便分析对比度增强后的视觉残留效应。观察者可对相似度相近的刺激物给出同等排序。在该成对排序协议中，每幅增强图像都会与其余图像逐一进行成对比较，最终将排序结果存储于偏好矩阵中。