回复: 为什么我的摄像头拍出来的视频方位好像和摄像头朝向不太一样？

import sensor, image, time

from image import SEARCH_EX, SEARCH_DS

thresholds = [(16, 50, 24, 99, -18, 67),
              (40, 65, -32, 32, 27, 82),
              (10, 27, -52, -16, -19, 99)]

sensor.reset()

sensor.set_pixformat(sensor.RGB565)
#sensor.set_pixformat(sensor.GRAYSCALE)

sensor.set_framesize(sensor.QQVGA)

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()

#templates = ["/left.pgm", "/right.pgm", "/band.pgm"] #保存多个模板
template1 = image.Image("left.pgm")
template2 = image.Image("right.pgm")
template3 = image.Image("band.pgm")
while(True):

    clock.tick()
    img = sensor.snapshot()
    for blob in img.find_blobs(thresholds, pixels_threshold=200, area_threshold=200):

        img.draw_rectangle(blob.rect())

        img.draw_cross(blob.cx(), blob.cy())

        if blob.code() == 1:
           print("前方为红灯")

        if blob.code() == 2:
           print("前方为黄灯")

        if blob.code() == 4:
           print("前方为绿灯")
        if blob.code()!=1 and blob.code()!=2 and blob.code()!=4:
            img = img.to_grayscale()
            r = img.find_template(template1, 0.10, step=4, search=SEARCH_EX) #, roi=(81, 49, 165, 166))
            if r:
                img.draw_rectangle(r)
                print("前方左转")
            r = img.find_template(template2, 0.10, step=4, search=SEARCH_EX) #, roi=(81, 49, 165, 166))
            if r:
                img.draw_rectangle(r)
                print("前方右转")
            r = img.find_template(template3, 0.10, step=4, search=SEARCH_EX) #, roi=(81, 49, 165, 166))
            if r:
                img.draw_rectangle(r)
                print("禁止通行")

我想问一下，在模板匹配中，如果没有识别到对应的图片，想要输出“未检测到标志”，elseif这一句该怎么写？（我图中并不能实现此功能）