使用opencv（图像处理）寻找轮廓

Question

我一直在使用opencv 实施一个项目“车牌检测器”。更新我的Python Version 和opencv 后，我在查找轮廓时遇到错误，如下所示：

imgContours, contours, npaHierarchy = cv2.findContours(imgThreshCopy, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)   # find all contours
ValueError: not enough values to unpack (expected 3, got 2)

这是我使用的代码：

def findPossibleCharsInScene(imgThresh):
listOfPossibleChars = []                # this will be the return value

intCountOfPossibleChars = 0

imgThreshCopy = imgThresh.copy()

imgContours, contours, npaHierarchy = cv2.findContours(imgThreshCopy, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)   # find all contours

height, width = imgThresh.shape
imgContours = np.zeros((height, width, 3), np.uint8)

for i in range(0, len(contours)):                       # for each contour

    if Main.showSteps == True: # show steps ###################################################
        cv2.drawContours(imgContours, contours, i, Main.SCALAR_WHITE)
    # end if # show steps #####################################################################

    possibleChar = PossibleChar.PossibleChar(contours[i])

    if DetectChars.checkIfPossibleChar(possibleChar):                   # if contour is a possible char, note this does not compare to other chars (yet) . . .
        intCountOfPossibleChars = intCountOfPossibleChars + 1           # increment count of possible chars
        listOfPossibleChars.append(possibleChar)                        # and add to list of possible chars
    # end if
# end for

if Main.showSteps == True: # show steps #######################################################
    print("\nstep 2 - len(contours) = " + str(len(contours)))  # 2362 with MCLRNF1 image
    print("step 2 - intCountOfPossibleChars = " + str(intCountOfPossibleChars))  # 131 with MCLRNF1 image
    cv2.imshow("2a", imgContours)
# end if # show steps #########################################################################

return listOfPossibleChars
# end function

我应该做哪些改变来纠正它？

Answer 1

我认为 cv2.findContours() 函数只返回 2 个值。您应该将代码更改为以下

contours, npaHierarchy = cv2.findContours(imgThreshCopy, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)