Evaluating the image quality is a very important problem in image and video processing. Numerous methods have been proposed over the past years to automatically evaluate the quality of images in agreement with human quality judgments. The purpose of this work is to present subjective and objective quality assessment methods and their classification. Eleven widely used and recommended by International Telecommunication Union (ITU) subjective methods are compared and described. Thirteen objective method is briefly presented (including MSE, MD, PCC, EPSNR, SSIM, MS-SSIM, FSIM, MAD, VSNR, VQM, NQM, DM, and 3D-GSM). Furthermore the list of widely used subjective quality data set is provided.

It is the foundation of tunnel engineering to classify the rock mass surrounding tunnels. However, it is not easy to precisely determine the class of rock mass in practice as sufficient geological exploration need to be completed before rock mass classification, and there exists some disputes referring to the rationalization of dozens of methods for rock mass classification through the world. The principles and procedures of the basic quality method, which are widely used in China, are presented in this paper, and the application process of the basic quality method is showed with a project case of Zhongnanshan highway tunnel which has operated in safety for nearly a decade. Then, both the advantages and disadvantages of the basic quality method are analyzed in terms of practical engineering applications. In consideration of the defects of the basic quality method, the concept of the subclassing of surrounding rock in grade III–V is developed in the end and the criterion is given to determine the subclass of rock mass. This study is aimed at providing some useful ideas and a reference for rock classification in highway tunnel engineering.