数字图像处理第二章课件.ppt

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1、R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals第2章 数字图像基础R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals2.1 Elements of Visual Perceptiion2.1 Elements of Visual Perceptiion人眼剖面简图角膜虹膜中央凹视网膜3层,平均直径20瞳孔2-8mm脉络

2、膜巩膜R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals视网膜上锥状体和柱状体的分布锥状体:昼视600-700万个中央凹,数码相机柱状体:夜视7500万-1.5亿,遍布视网膜R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals人眼的针孔成像人眼的针孔成像摄像机成象几何(凸透镜):其中:成象的物距物距u,像距像距v,焦距焦距f

3、 称为系统的放大系数简化（只有光心有光通过，图象聚在焦平面上），针孔模型：（光学成象）u v,fR.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals主观主观(感觉感觉)亮度范围呈现自适应层次亮度范围呈现自适应层次人眼主观(感觉)亮度是入射光强的对数函数.能同时鉴别的光强级范围很小主观亮度强闪光极限夜视阈值适应范围夜视昼视对数光强R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2

4、:Digital Image Fundamentals刻画亮度分辨率的基本实验刻画亮度分辨率的基本实验亮度分辨力实验,具有恒定背景的对比灵敏度R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals作为光强函数的典型韦伯比作为光强函数的典型韦伯比昼视与夜视分段韦伯比(I/I):在相当宽的范围内约为2%R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image F

5、undamentals感觉亮度不是光强的简单函数感觉亮度不是光强的简单函数人眼响应在不同光强区的边界周围会”过量调整”.这种现象称为”马赫效应马赫效应”Ernst Mach(1865描述)R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals同时对比度的示例同时对比度的示例R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals光学

6、错觉光学错觉:R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image FundamentalsIs there a face on Mars 1997R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentalshttp:/1998.4R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter

7、 2:Digital Image Fundamentals2.2 Light and Electromagnetic Spectrum2.2 Light and Electromagnetic SpectrumR.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals波长波长电磁波长与频率R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamen

8、tals2.3.Image Sensing and Acquisition2.3.Image Sensing and Acquisition三种传感器排列R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals单点传感器与运动结合产生2维图像R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals线状/环状传感器(1维)R.C.Gon

9、zalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image FundamentalsImage Acquisition Using Sensor ArraysImage Acquisition Using Sensor ArraysR.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals一种简单的成像模型物理响应f(x,y)应该满足:0f(x,y)f(x,y)=i(x,y)r

10、(x,y)其中 0i(x,y)and 0r(x,y)1Lmin=l=0(D(p,q)=0,iff p=q)D(p,q)=D(q,p),andD(p,z)=D(p,q)+D(q,z)例如用LM范数表示的通用Minkowski距离:M=1,2,的LM距离最有用,分别对应:R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals欧氏euclidean距离L2:等距为圆:bw=zeros(200,200);bw(50,50)=1;bw(50,150)=1;bw(150,1

11、00)=1;D1=bwdist(bw);准欧氏距离:quasi-euclidean等距为8边形D2=bwdist(bw,quasi-uclidean);R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals街区City-Block距离L1:等距为4角星棋盘chessboard距离L:等距为矩形R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fund

12、amentalsR.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentals2.6 Linear and Nonlinear Operations线性与非线性运算Let H be an operator whose input and output are images.H is linear if,for any two images f and g and two scales a and b,H(af+bg)=aH(f)+bH(g)An operator that fails the test is nonlinear例如,计算k幅图像之和的运算是线性的;计算2幅图像之差的绝对值的运算是非线性的.R.C.Gonzalez,R.E.WoodsChapter 2:Digital Image FundamentalsChapter 2:Digital Image Fundamentalshomework1Page 55-57习题 2.3 2.6 2.7(+2.8)参考Dipum Project2.4 2.15