噪声概率密度函数一空间独立的噪声 瑞利噪声 p2) p() p() 1 0.607、6 p(2) - a)e-(2-a)2/b z≥a Gaussian Rayleigh Erlang(Gamma) 0.607 0 K= a(b-1)- e- (b-1)1 +00 E(z)= zp(z)dz (b-1)/a -00 +00 p(z) P() p(z) D(z)= (z-2p(z)dz 1-(P+P) Exponential b-a Uniform Salt-and. P pepper 均值z=a+√πb/a 方差2= b(4-π) abe de f 4 FIGURE 5.2 Some important probability density functions.噪声概率密度函数—空间独立的噪声 瑞利噪声 均值 𝑝(𝑧) = ቐ 2 𝑏 𝑧 − 𝑎 𝑒 − 𝑧−𝑎 Τ 2 𝑏 𝑧 ≥ 𝑎 0 𝑧 < 𝑎 方差 𝑧ҧ= 𝑎 + 𝜋𝑏/𝑎 𝜎 2 = 𝑏(4 − 𝜋) 4 𝐸(𝑧) = න −∞ +∞ 𝑧𝑝 𝑧 𝑑𝑧 𝐷 𝑧 = න −∞ +∞ 𝑧 − 𝑧ҧ 2𝑝 𝑧 𝑑𝑧