冈萨版数字图像处理—双语课程复习.ppt

Due to processing, storage, and sampling hardware considerations, the number of gray levels typically is an integer power of 2: L = 2k, k is called the bit depth. ;A set of pixels all of which are 4-connected to each other is called a 4-component; if all the pixels are 8-connected the set is an 8-component.;1. The Euclidean distance between p and q is defined as:;2. The D4 distance (also called city block distance) between p and q is defined as:;3. The D8 distance (also called chessboard distance) between p and q is defined as: D8(p,q) = max( x-s , y-t );p2;Contrast stretching (对比拉伸);Illustration of histogram equalization;9;Output image ; 255 194 157 103 15 59 116 202 239 90 155 5 235 234 207 124 209 188 105 3 227 113 45 228 35;Moving window example: find the minimum;17;Illustration of Median filter;Definition: highlight fine detail in an image or to enhance detail that has been blurred. It is the opposite of averaging.;Implementing the Fourier transform;Application of translation property;The discrete Fourier transform;Periodicity;The idea of conjugate symmetry was introduced in previous section, and is repeated here for convenience: F(u, v) = F*(-u, -v);Components characteristics;The need for padding (补零);Padding of 2-D functions;The periodic sequences are formed by extending f(x,y) and h(x,y) as follows:;Estimating the degradation function;In order to reduce the effect of noise in our observation, we would look for areas of strong signal content in the degraded image, soη(x,y) is ignored. Using sample gray levels of the object and background, we can construct an unblurred subimage. Let the observed subimage be denoted by gs(x,y), and the constructed subimage be denoted by;1. Using an image acquiring device to get a similar degraded image by adjusting system parameter settings.;Estimation by modeling (建模);Definition of Inverse filtering (逆滤波);Problems: 1) F(u,v) is a random function whose F