2点运算和直方图 ●●●●● ●●●● ●●● ●●●● k Histogram Channel: Gray DB=12×D4+50 Mean:203.72 eve std Dey: 42.32 Count Median: 213 Percentile Pixels: 16384 Cache level: 1 213≈1.2*138+502 点运算和直方图 D D B A =  + 1.2 50 213≈1.2*138+50