LetNet Example

import sensor, image, time

sensor.reset() # Reset and initialize the sensor.
sensor.set_contrast(3)
sensor.set_pixformat(sensor.GRAYSCALE) # Set pixel format to RGB565 (or GRAYSCALE)
sensor.set_framesize(sensor.VGA) # Set frame size to QVGA (320x240)
sensor.set_windowing((128, 128)) # Set 128x128 window.
sensor.skip_frames(time = 2000) # Wait for settings take effect.
sensor.set_auto_gain(False)
sensor.set_auto_exposure(False)

while(True):
img = sensor.snapshot()
# NOTE: Uncomment to detect dark numbers on white background
# img.invert()
out = img.find_number(roi=(img.width()//2-14, img.height()//2-14, 28, 28))
img.draw_rectangle((img.width()//2-15, img.height()//2-15, 30, 30))
if out[1] > 5: # Confidence level
print("Number: %d Confidence: %0.2f" %(out[0], out[1]))

报错提示
Traceback (most recent call last):
File "", line 17, in
AttributeError: 'Image' object has no attribute 'find_number'
MicroPython v1.9.4-4510-g23e8457de on 2018-06-29; OPENMV3 with STM32F765
Type "help()" for more information.