分段线性灰度变换 M-d lM-6(x2)-61+d bsf(xveMs d-c g(x, y) [f(x,y)-a]+ a≤f(x,y)<b f(,y) 0≤f(x,y)<a                   f x y f x y a a c f x y a c a f x y b b a d c f x y b d b f x y M M b M d g x y f f g ( , ) 0 ( , ) [ ( , ) ] ( , ) [ ( , ) ] ( , ) ( , ) 分段线性灰度变换