使用OpenCV(图像处理)查找轮廓

Question

我一直在使用opencv实施的项目"汽车号板检测器"。更新我的Python Version和opencv后，我在查找轮廓时会遇到错误：

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

我应该做什么更改来纠正它？

Answer 1

我认为cv2.findcontours（）函数仅返回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)