I am trying to detect movement on screen but get an error: ValueError: too many values to unpack (expected 4)

Question

我正在使用的模块：PIL、cv2、numpy 和 time 我制作了这个小代码，可以捕捉屏幕上的运动，如果某人或某物移动，它会在 cv2 认为移动的对象上放置级联。

我的代码：

from PIL import ImageGrab
import cv2
import numpy as np
import time


def Screen():
    while 1:
        Screen =  np.array(ImageGrab.grab(bbox=(13, 32,805, 623)))
        cv2.imshow(" ",cv2.cvtColor(Screen, cv2.COLOR_BGR2RGB))
        gray = cv2.cvtColor(Screen, cv2.COLOR_BGR2GRAY)

        last_time = time.time()

        print("Fps: " + str(last_time))

        for (x,y,w,h) in gray:
            cv2.rectangle(Screen,(x,y),(x+w,y+h),(0,255,0),2)

        pass

        k = cv2.waitKey(30) & 0xff

        if k == 27:
            break

    cv2.destroyAllWindows()

Screen()

我得到的错误：

for (x,y,w,h) in gray:

ValueError: too many values to unpack (expected 4)

Answer 1

首先，假设您的意思是 w,h (width, height) ，您可以获得 w,h 而无需使用以下方法遍历图像：

w,h = gray.shape

第二件事是gray实际上是一个二维numpy数组，包含数组中相应位置每个像素的值

如果你想为每个 x,y, val 遍历图像，你可以这样实现：

for y, row in enumerate(image):
  for x, pixel_val in enumerate(row):
     # do whatever you want you have w,h,x,y, pixel_val

如果您不需要pixel_val，那么只需简单地循环超越限制而不涉及图像

for y in range(h):
    for x in range(w):
         # do processing here you have w,h,x,y

I am trying to detect movement on screen but get an error: ValueError: too many values to unpack (expected 4)

I am trying to detect movement on screen but get an error: ValueError: too many values to unpack (expected 4)

python

opencv

numpy

python-imaging-library

cv2