A survey of visual lip reading and lip-password verification

In this paper, we have reviewed the main process of visual lip reading and lip motion password (simply called lip-password hereinafter) verification that is the useful and flexible method to apply in many applications, especially in security field since it can do double checks to verify both the speaker and his/her password. The reviewed content includes selectively significant preprocessing, visual feature extractions, and classification schemes that are all important parts in this tasks' processes.