3 Image Enhancement 3.Intensity transformations spatial filtering Background Some basic intensity transformation Histogram-based image enhancement Fundamentals of spatial filtering Smoothing spatial filters Sharpen spatial filters 第3章第1页
3 Image Enhancement 第3章 第1页 3. Intensity transformations & spatial filtering Background Some basic intensity transformation Histogram-based image enhancement Fundamentals of spatial filtering Smoothing spatial filters Sharpen spatial filters
3 Image Enhancement 3.4 Fundamentals of spatial filtering >Spatial filters vs.frequency filters 1)one-to-one correspondence in many cases 2)Spatial filters offer considerably more versatility because they can be used also for nonlinear filtering,something we cannot do in the frequency domain 第3章第2页
3 Image Enhancement 第3章 第2页 3.4 Fundamentals of spatial filtering Spatial filters vs. frequency filters 1) one-to-one correspondence in many cases 2) Spatial filters offer considerably more versatility because they can be used also for nonlinear filtering, something we cannot do in the frequency domain
3 Image Enhancement 3.4 Fundamentals of spatial filtering Filter(滤波器) Mask(掩模) Kernel(核) Template(模板) Window(窗口) .y g(x,y)=1(-1,-1)f(x-1y-1)+w(-1,0)f(x-1,y)+.+w(0,0)f(x,y)+.+(1,0)f(x+1y)+w1,1)fx+1,y+1）
3 Image Enhancement 3.4 Fundamentals of spatial filtering Filter (滤波器) Mask (掩模) Kernel (核) Template (模板) Window (窗口) g x y w f x y w f x y w f x y w f x y w f x y ( , ) ( 1, 1) ( 1, 1) ( 1,0) ( 1, ) ... (0,0) ( , ) ... (1,0 ) ( 1, ) (1,1) ( 1, 1)
3 Image Enhancement 3.4 Fundamentals of spatial filtering The general form of linear filtering 给定输入图像f(x,y),和尺寸为mxn的模板w(i,),则 滤波后的输出图像g(x,y)为： gx,)=2立s0fx+s,y+0 S=-at=-b m-1 b=n-1 其中： a= 2) 2 m和n通常取奇数，为什么？
3 Image Enhancement 3.4 Fundamentals of spatial filtering The general form of linear filtering 给定输入图像f(x,y),和尺寸为mn的模板w(i,j), 则 滤波后的输出图像g(x,y)为: ( , ) ( , ) ( , ) s a b s a t b g x y w s t f x s y t 1 2 m a 1 2 n b m和n通常取奇数，为什么？ 其中: ，
3 lmage Enhancement 3.4 Fundamentals of spatial filtering 如何处理卷积滤波的边界问题？ 3x3 mask 8x8 image 第3章第5页
3 Image Enhancement 第3章 第5页 如何处理卷积滤波的边界问题? 33 mask 88 image 3.4 Fundamentals of spatial filtering