说明：  Textural Features for Image Classification
(Texture is one of the important characteristics used in identifying objects or regions of interest in an image, whether the image be a photomicrograph, an aerial photograph, or a satellite image. This paper describes some easily computable textural features based on gray- tone spatial dependancies, and illustrates their application in category- identification tasks of three different kinds of image data: photo- micrographs of five kinds of sandstones,)