Aihua_DIP2-DigitalImageFundamentals解释.pptVIP

D4 distance (city-block distance) the pixels having a D4 distance from (x, y) less than or equal to some value r form a diamond centered at (x, y). Eg：D4 distance ≤ 2 from (x, y) (the center point 0)： The pixels with D4 =1 are the 4-neighbors of (x, y). D8 distance (chessboard distance) the pixels withD8 distance from (x, y) less than or equal to some value r form a square centered at (x, y). Eg：D8 distance ≤ 2 from (x, y) (the center point 0)： The pixels with D8 =1 are the 8-neighbors of (x, y). Dm distance Note: the D4 and D8 distances are independent of any paths(points) since only coordinates involved. However, Dm distance: the shortest m-path between the points. Depend on the points(values) Eg: assume that p, p2 , and p4 have value 1, V={1} p1=p3=0: Dm(p, p4) = 2(pp2p4) p1=1, p3=0: Dm(p, p4) = 3 (pp1p2p4) p1=0,p3=1: Dm(p, p4) = 3 (pp2p3p4) p1=p3=1: Dm(p, p4) = 4 (pp1p2p3p4) 0 0 0 0 0 0 0 p3 p4(1) 0 0 p1 p2(1) 0 0 0 p(1) 0 0 0 0 0 0 0 0 2.5.4 Image operation on a pixel basis Arithmetic and logic operations are similarly defined between corresponding pixels in the images involved. “dividing one image by another,”: specifically the division is carried out between corresponding pixels in the two images. 2.6 Linear and Nonlinear Operations Let H be an operator. H is said to be a linear operator if, for any two images f and g and any two scalars a and b, An operator that fails the above test is by definition nonlinear. Eg: The sum of K images is a linear operator. The absolute value of the difference of two images is not. Summary We have looked at: Human visual system Light and the electromagnetic spectrum Image sensing and acquisition Sampling, quantisation and resolution Basic relationship between pixels Next time we start to look at techniques for image enhancement * 1.The cornea： is a tough, transparent tissue that covers the anterior surface of the eye. Continuous with the cornea, the scler