1引言 ●●●●● ●●●● ●●● ●●● ●●●● lenna. bmp Dn,=D,+50 D=1.5×D4D=0.8×D4D=-1×D4+2551 引言 D D B A = +50 D D B A =  1.5 D D B A =  0.8 D D B A = −  + 1 255 lenna.bmp