请问编译的时候为什么会出现'blob' object has no attribute 'pixel'?

[za5u]

import sensor, image, time
import car
from pyb import LED
from pyb import Pin

sensor.reset() # Initialize the camera sensor.
sensor.set_pixformat(sensor.RGB565) # use RGB565.
sensor.set_framesize(sensor.QQVGA) # use QQVGA for speed.
sensor.skip_frames(10) # Let new settings take affect.
sensor.set_auto_whitebal(False) # turn this off.
clock = time.clock() # Tracks FPS.

green_threshold   = (31, 66, -34, -9, -2, 18)

def find_max(blobs):    #寻找最大面积的球
    max_size=0
    for blob in blobs:
        if blob[2]*blob[3] > max_size:
            max_blob=blob
            max_size = blob[2]*blob[3]
    return max_blob

while(True):

    clock.tick() # Track elapsed milliseconds between snapshots().
    img = sensor.snapshot() # Take a picture and return the image.
    
    blobs = img.find_blobs([green_threshold])
    if blobs:
        max_blob = find_max(blobs)
        x_error = max_blob[5]-img.width()/2        
        for greenblord_threshold in  blobs:
            if greenblord_threshold.pixel() > 2000:
                car.run(30-0.5*green_x_error,30+0.5*green_x_error)
	
            elif greenblord_threshold.pixel() < 10000:
                car.run(0,0)
    else:
        car.run(20,-20)

[kidswong999]

使用最新的固件。