Perceptual Criteria on Image Compression

Nowadays, digital images are used in many areas in everyday life, but they tend to be big. This increment of the amount of information leads us to the problem of image data storage. An important feature of image compression is that it can be lossy or lossless. A compressed image is acceptable provided these losses of image information are not perceived by the eye. It is possible to assume that a portion of this information is redundant. In lossy compression, current image compression schemes remove information considered irrelevant by using mathematical criteria. One of the problems of these schemes is that although the numerical quality of the compressed image is low, it shows a high visual image quality, e.g. it does not show a lot of visible artifacts. It is because these mathematical criteria, used to remove information, do not take into account if the viewed information is perceived by the Human Visual System. Therefore, the aim of the PHi-SET image compression scheme is for obtaining images that do not show artifacts although their numerical quality is low, eliminating information that is not vosible by the Human Visual System.