The appearance of objects in underwater images is degraded by the selective attenuation of light, which reduces contrast and causes a colour cast. This degradation depends on the water environment, and increases with depth and with the distance of the object from the camera. Despite an increasing volume of works in underwater image enhancement and restoration, the lack of a commonly accepted evaluation measure is hindering the progress as it is difficult to compare methods. In this paper, we review commonly used colour accuracy measures, such as colour reproduction error and CIEDE2000, and no-reference image quality measures, such as UIQM, UCIQE and CCF, which have not yet been systematically validated. We show that none of the no-reference quality measures satisfactorily rates the quality of enhanced underwater images and discuss their main shortcomings. Images and results are available at https://puiqe.eecs.qmul.ac.uk.
翻译:水下图像中物体的外观由于有选择地淡化光线而退化,这减少了对比度并造成色化。这种退化取决于水环境,随着深度和距离与相机的距离而增加。尽管水下图像增强和恢复的工程量不断增加,但缺乏普遍接受的评价措施阻碍了进展,因为难以比较方法。在本文中,我们审查了常用的颜色精确度度度度量,如彩色复制错误和CEEEDE2000,以及未参照的图像质量度量,如UIQM、UCIQE和CCF,这些措施尚未得到系统的验证。我们表明,没有任何一项无参照质量措施令人满意地衡量水下放大图像的质量,并讨论其主要缺点。图像和结果可在https://puiqe.eecs.qmul.ac.uk查阅。