@kidswong999 请问哪里出了问题

@kidswong999

# Untitled - By: wx601 - 周日 2月 17 2019

import sensor, image, time

#颜色追踪的例子，一定要控制环境的光，保持光线是稳定的
red_threshold = (40, 74, 22, 64, -6, 18)
sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)
sensor.skip_frames(time = 2000)
sensor.set_auto_gain(False) # must be turned off for color tracking
sensor.set_auto_whitebal(False) # must be turned off for color tracking
clock = time.clock()
clock = time.clock()

while(True):
    clock.tick()
    img = sensor.snapshot()
    gray =img.rgb_to_grayscale()
    rectanges = gray.find_rects()
    for rectange in rectanges :
        area = rectange.rect()
        blobs = img.find_blobs([red_threshold],roi=area,x_stride=5,y_stride=5)
        if blobs:
            for blob in blobs:
                img.draw_rectangle(blob.rect())#, color=White
                img.draw_cross(blob.cx(), blob.cy(), size=5)

@kidswong999 就是这行代码出现了错误

gray = rgb_to_grayscale(img)