萌新求助，openmv怎么同时识别最大和次大的色块。

[fwzd]

# Blob Detection and uart transport
import sensor, image, time
from pyb import UART
import json
# For color tracking to work really well you should ideally be in a very, very,
# very, controlled enviroment where the lighting is constant...
yellow_threshold   =(3, 53, 6, 47, 14, 77)
# You may need to tweak the above settings for tracking green things...
# Select an area in the Framebuffer to copy the color settings.

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.

uart = UART(3, 115200)
def find_max(blobs):
    max_size=0
    for blob in blobs:
        if blob.pixels() > max_size:
            max_blob=blob
            max_size = blob.pixels()
    return max_blob

def find_second(blobs):
    blobs.remove(max_blob)
    second_blob=find_max(blobs)
    return second_blob
    
while(True):
    img = sensor.snapshot() # Take a picture and return the image.

    blobs = img.find_blobs([yellow_threshold])
    if blobs:
        max_blob=find_max(blobs)
        second_blob=find_second(blobs)
        print('sum :', len(blobs))
        img.draw_rectangle(max_blob.rect())
        img.draw_cross(max_blob.cx(), max_blob.cy())

        output_str="[%d,%d]" % (max_blob.cx(),max_blob.cy()) #方式1
        #output_str=json.dumps([max_blob.cx(),max_blob.cy()]) #方式2
        print('you send:',output_str)
        uart.write(output_str+'\r\n')
    else:
        print('not found!')

请问怎么写才能同时识别最大和次大色块？谢谢各位大佬

[kidswong999]

你没必要写一个函数的。

所以你函数写的有问题，变量没有定义。

[fwzd]

@kidswong999 请问remove那个是直接写到find_max函数里面吗

[kidswong999]

uart = UART(3, 115200)
def find_max(blobs):
    max_size=0
    for blob in blobs:
        if blob.pixels() > max_size:
            max_blob=blob
            max_size = blob.pixels()
    return max_blob
while(True):
    img = sensor.snapshot() # Take a picture and return the image.

    blobs = img.find_blobs([yellow_threshold])
    if blobs:
        max_blob=find_max(blobs)
        blobs.remove(max_blob)
        second_blob=find_max(blobs)
        print(max_blob)
        print(second_blob)
    else:
        print('not found!')

[fwzd]

@kidswong999 您好，按这个可是还是报相同的错误

[kidswong999]

因为如果只有一个色块，删掉了一个，就是空的数组，find_max函数就会报错。

find_max 函数改一下。

def find_max(blobs):
    max_size=0
    max_blob = None
    for blob in blobs:
        if blob.pixels() > max_size:
            max_blob=blob
            print(max_blob)
            max_size = blob.pixels()
    return max_blob

[fwzd]

@kidswong999 这个样子的话，输出0个或者2个都没有问题，但是只有1个色块时就会报错

[kidswong999]

是啊，second_blob是None，当然不能用来画框

[fwzd]

@kidswong999 嗯嗯 谢谢你啦

[13542749802]

@kidswong999 在 萌新求助，openmv怎么同时识别最大和次大的色块。 中说：

second_blob

second_blob为什么是为None呢