@yuan 难道不是因为image是类，而find_rects是类的实例才能使用吗

import sensor, image, time

sensor.reset()
sensor.set_pixformat(sensor.GRAYSCALE)
sensor.set_framesize(sensor.QVGA)
sensor.skip_frames(time = 2000)

clock = time.clock()

while(True):
    clock.tick()
    img = sensor.snapshot()
    img.grayscale_to_binary(128)
    print(clock.fps())