，明白了，谢谢前辈

每次调用sensor.snapshot()函数返回的图像为啥是同一个地址，使用img.mean()函数时也只是对那一段内存进行处理

import sensor, image, time
sensor.reset() # 初始化sensor
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QQVGA)
sensor.skip_frames(time = 2000)
clock = time.clock()
while(True):
clock.tick()
img = sensor.snapshot() # 拍一张照片，返回图像
img1 = img.mean(2)#均值滤波后的图像
for i in range(0,img.width()):
for j in range(0,img.height()):
tuple1 = img.get_pixel(i,j)
tuple2 = img1.get_pixel(i,j)
tuple3 = (tuple1[0]-tuple2[0],tuple1[1]-tuple2[1],tuple1[2]-tuple2[2])
print(tuple1)
print(tuple2)
print(tuple3)
print(clock.fps())

import sensor, image, time
sensor.reset() # 初始化sensor
sensor.set_pixformat(sensor.RGB565) 
sensor.set_framesize(sensor.QQVGA) 
sensor.skip_frames(time = 2000)
clock = time.clock() 
while(True):
    clock.tick() 
    img = sensor.snapshot() # 拍一张照片，返回图像
    img1 = img.mean(2)#均值滤波后的图像
    for i in range(0,img.width()):
        for j in range(0,img.height()):
            tuple1 = img.get_pixel(i,j)
            tuple2 = img1.get_pixel(i,j)
            tuple3 = (tuple1[0]-tuple2[0],tuple1[1]-tuple2[1],tuple1[2]-tuple2[2])
            print(tuple1)
            print(tuple2)
            print(tuple3)
    print(clock.fps())