Extending quality metrics to full luminance range images
Many quality metrics take as input gamma corrected images and<br> assume that pixel code values are scaled perceptually uniform. <br> Although this is a valid assumption for darker displays<br> operating in the luminance range typical for CRT displays (from 0.1<br> to 80 $cd/m^2$), it is no longer true for much brighter LCD displays<br> (typically up to 500 $cd/m^2$), plasma displays (small regions up to<br> 1000 $cd/m^2$) and HDR displays (up to 3000 $cd/m^2$). The<br> distortions that are barely visible on dark displays become clearly<br> noticeable when shown on much brighter displays. To estimate quality<br> of images shown on bright displays, we propose a straightforward<br> extension to the popular quality metrics, such as PSNR and SSIM,<br> that makes them capable of handling all luminance levels visible to<br> the human eye without altering their results for typical CRT display<br> luminance levels. Such extended quality metrics can be used to<br> estimate quality of high dynamic range (HDR) images as well as<br> account for display brightness.