cv2.getTrackbarPos 的 Python OpenCV Trackbar 错误

Question

我正在尝试在 Windows 10 PC 上使用 Visual Studio Code 执行以下 Python 3.9.5 脚本：

import cv2
import numpy as np

frameWidth = 640
frameHeight = 480
cap = cv2.VideoCapture(1)
cap.set(3, frameWidth)
cap.set(4, frameHeight)


def empty(a):
    pass

cv2.namedWindow("HSV")
cv2.resizeWindow("HSV", 640, 240)
cv2.createTrackbar("HUE MIN", "HSV", 0, 179, empty)
cv2.createTrackbar("HUE Max", "HSV", 129, 129, empty)
cv2.createTrackbar("SAT Min", "HSV", 0, 255, empty)
cv2.createTrackbar("SAT Max", "HSV", 255, 255 ,empty)
cv2.createTrackbar("VALUE Min", "HSV", 0, 255, empty)
cv2.createTrackbar("VALUE Max", "HSV", 255, 255, empty)

cap = cv2.VideoCapture('vid1.mp4')
frameCounter = 0

while True:
    frameCounter +=1
    if cap.get(cv2.CAP_PROP_FRAME_COUNT) == frameCounter:
        cap.set(cv2.CAP_PROP_POS_FRAMES, 0)
        frameCounter=0

    _, img = cap.read()
    imgHsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)

    h_min = cv2.getTrackbarPos("HUE Min", "HSV")
    h_max = cv2.getTrackbarPos("HUE Max", "HSV")
    s_min = cv2.getTrackbarPos("SAT Min", "HSV")
    s_max = cv2.getTrackbarPos("SAT Max", "HSV")
    v_min = cv2.getTrackbarPos("VALUE Max", "HSV")
    v_max = cv2.getTrackbarPos("VALUE Max", "HSV")
    print(h_min)

    lower = np.array([h_min, s_min, v_min])
    upper = np.array([h_max, s_max, v_max])
    mask = cv2.inRange(imgHsv, lower, upper)
    result = cv2.bitwise_and(img, img, mask=mask)

    mask = cv2.cvtColor(mask, cv2.COLOR_GRAY2BGR)
    hstack = np.hstack([img, mask, result])
    cv2.imshow('Horizontal Stacking', hstack)
    if cv2.waitKey(1) and 0xFF == ord('q'):
        cv2.waitKey(0)

cap.release()
cv2.destroyAllWindows()

但是，在执行时，我收到以下错误：

[ WARN:0@0.229] global D:\a\opencv-python\opencv-python\opencv\modules\videoio\src\cap_msmf.cpp (539) `anonymous-namespace'::SourceReaderCB::~SourceReaderCB terminating async callback
Traceback (most recent call last):
  File "c:...\ColorPickerScript.py", line 35, in <module>
    h_min = cv2.getTrackbarPos("HUE Min", "HSV")
cv2.error: OpenCV(4.5.5) D:\a\opencv-python\opencv-python\opencv\modules\highgui\src\window.cpp:862: error: (-215:Assertion failed) trackbar in function 'cv::getTrackbarPos'

我希望有人能指出正确的方向，以找出发生这种情况的原因以及我能做些什么来解决它。我还没有找到任何解决方案，谢谢！

Answer 1

正如 Christoph Rackwitz 所指出的，问题在于我制作了一种类型，其中一个字符串全部大写，但没有另一个。更正此问题即可解决问题。