import sensor, image, time

sensor.reset()
sensor.set_pixformat(sensor.RGB565)
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()

while(True):
    clock.tick()
    img = sensor.snapshot()
    for r in img.find_rects(threshold = 2000):
        area =r.rect() #(r.x(),r.y(),r.w(),r.h())
        L = (r[2]+r[3])/2
        l=int(1000/L)
        statistics = img.get_statistics(roi=area)#像素颜色统计
        if 38<statistics.l_mode()<55 and 34<statistics.a_mode()<68 and -15<statistics.b_mode()<55:#if the circle is red
            img.draw_rectangle(area, color = (255, 0, 0))
            print("FPS %f" % clock.fps())

报错的关键字是：OSError: Invalid roi dimensions
程序有时候运行没问题 有时候运行着就报这个错