应该是sensor进灰了，按照视频1分10秒中的方法，擦干净就行。
https://singtown.com/learn/49985/

import sensor, image, time

sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)
sensor.skip_frames(time = 2000)

clock = time.clock()
i=0
while(True):
    clock.tick()
    img = sensor.snapshot()
    img.save(str(i)+'.jpg')
    i++
    print(clock.fps())

@laoguren1122 程序如图
import time, sensor, image, math
from image import SEARCH_EX, SEARCH_DS

Reset sensor

sensor.reset()

Set sensor settings

sensor.set_contrast(1)
sensor.set_gainceiling(16)

Max resolution for template matching with SEARCH_EX is QQVGA

sensor.set_framesize(sensor.QQVGA)

You can set windowing to reduce the search image.

#sensor.set_windowing(((640-80)//2, (480-60)//2, 80, 60))
sensor.set_pixformat(sensor.GRAYSCALE)

Load template.

Template should be a small (eg. 32x32 pixels) grayscale image.

template = image.Image("/ball3.pgm")

low_threshold = (0, 50)
high_threshold = (195, 255)

clock = time.clock()

Run template matching

while (True):
clock.tick()
img = sensor.snapshot().lens_corr(1.8)

for x in range(4):

r = img.find_template(template, 0.70)
if r:
    img.draw_rectangle(r,color=0)

img.find_edges(image.EDGE_CANNY, threshold=(50, 80))

for c in img.find_circles(threshold = 2500, x_margin = 20, y_margin = 20, r_margin = 20):

img.draw_circle(c.x(), c.y(), c.r(), color = (0, 0, 0))

print(c)

print(clock.fps())

确实是白平衡的问题。因为OpenMV开机会自动调节白平衡，如果一开机就全部是红色的，白平衡就会自动偏蓝。

解决办法：手动设置白平衡。

代码：

import sensor,time
sensor.reset()
sensor.set_pixformat(sensor.RGB565) #使用RGB565
sensor.set_framesize(sensor.QVGA) #使用QQVGA
sensor.set_auto_whitebal(False, rgb_gain_db = (-6.02073, -5.886325, -4.30291))
clock = time.clock()

while(True):
    clock.tick()
    img = sensor.snapshot()
    print(clock.fps())

这个rgb_gain_db的参数是我的环境正常的,颜色比较鲜艳。如果你想修改，可以运行这个代码获得：https://book.openmv.cc/example/21-Sensor-Control/sensor-manual-whitebal-control.html

如果要关闭摄像头，可以让摄像头休眠。一般不需要。https://book.openmv.cc/example/19-Low-Power/sensor-sleep.html

import time, sensor, image
from image import SEARCH_EX, SEARCH_DS


sensor.reset()


sensor.set_contrast(1)
sensor.set_gainceiling(16)

sensor.set_framesize(sensor.VGA)

sensor.set_pixformat(sensor.GRAYSCALE)


clock = time.clock()


while (True):
    clock.tick()
    img = sensor.snapshot(copy_to_fb=False)
    print(clock.fps())

提供一下全部代码。要文本，不要图片。
和OpenMV的的硬件型号，sensor模组的型号。

@kidswong999

import sensor, image, time

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.

face_cascade = image.HaarCascade("frontalface", stages=25)



while(True):


    clock.tick() # Track elapsed milliseconds between snapshots().
    img = sensor.snapshot() # Take a picture and return the image.
    
    objects = sensor.snapshot().to_grayscale().find_features(face_cascade, threshold=0.75, scale=1.35)
   
    if objects:
        print("检测到人脸")
    
    for code in img.find_qrcodes():
        message = code.payload()
        print(message)
    
    
   

# This code run in OpenMV4 H7 

import sensor, image, time, os, tf

sensor.reset()                         # Reset and initialize the sensor.
sensor.set_pixformat(sensor.GRAYSCALE)    # Set pixel format to RGB565 (or GRAYSCALE)
sensor.set_framesize(sensor.QVGA)      # Set frame size to QVGA (320x240)
sensor.set_windowing((240, 240))       # Set 240x240 window.
sensor.skip_frames(time=2000)          # Let the camera adjust.

clock = time.clock()
while(True):
    clock.tick()
    img = sensor.snapshot().binary([(0,64)])
    for obj in tf.classify("trained.tflite", img, min_scale=1.0, scale_mul=0.5, x_overlap=0.0, y_overlap=0.0):
        output = obj.output()
        number = output.index(max(output))
        print(number)
    print(clock.fps(), "fps")

@kidswong999
IDE中的：example/video_recording/gif.py
源码：
import sensor, image, time

sensor.reset()
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QVGA)
sensor.skip_frames(time = 2000)
clock = time.clock()

while(True):
clock.tick()
img = sensor.snapshot()
print(clock.fps())