使用轨迹栏检测颜色并找到所需颜色的轮廓

Question

我想使用轨迹栏选择所需的颜色，然后获得带有x和y坐标的轮廓。当我运行代码时，出现下一个错误：

contours, _ = cv2.findContours(bin, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
cv2.error: OpenCV(4.2.0) C:\projects\opencv-python\opencv\modules\imgproc\src\contours.cpp:197: error: 
(-210:Unsupported format or combination of formats) [Start]FindContours supports only CV_8UC1 images when mode != CV_RETR_FLOODFILL otherwise supports CV_32SC1 images only in function 'cvStartFindContours_Impl'

用于检测轮廓的输入图像是二进制的，所以我不知道我在这里做错了什么。这是我使用的代码：

import cv2
import numpy as np

def nothing(x):
    pass

cv2.namedWindow("Tracking")
cv2.createTrackbar("LH", "Tracking", 0, 255, nothing)
cv2.createTrackbar("LS", "Tracking", 0, 255, nothing)
cv2.createTrackbar("LV", "Tracking", 0, 255, nothing)
cv2.createTrackbar("UH", "Tracking", 255, 255, nothing)
cv2.createTrackbar("US", "Tracking", 255, 255, nothing)
cv2.createTrackbar("UV", "Tracking", 255, 255, nothing)

while True:
    frame = cv2.imread('3blobs.jpg',1)
    font = cv2.FONT_HERSHEY_COMPLEX
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

    l_h = cv2.getTrackbarPos("LH", "Tracking")
    l_s = cv2.getTrackbarPos("LS", "Tracking")
    l_v = cv2.getTrackbarPos("LV", "Tracking")

    u_h = cv2.getTrackbarPos("UH", "Tracking")
    u_s = cv2.getTrackbarPos("US", "Tracking")
    u_v = cv2.getTrackbarPos("UV", "Tracking")

    l_b = np.array([l_h, l_s, l_v])
    u_b = np.array([u_h, u_s, u_v])

    mask = cv2.inRange(hsv, l_b, u_b)

    res = cv2.bitwise_and(frame, frame, mask=mask)
    trash, bin = cv2.threshold(res, 227, 255, 1, cv2.THRESH_BINARY)

    # Detecting contours in image.
    contours, _ = cv2.findContours(bin, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

    # Going through every contours found in the image.
    for cnt in contours:

        approx = cv2.approxPolyDP(cnt, 0.009 * cv2.arcLength(cnt, True), True)

        # draws boundary of contours.
        cv2.drawContours(frame, [approx], 0, (0, 0, 255), 2)

        # Used to flatted the array containing
        # the co-ordinates of the vertices.
        n = approx.ravel()
        i = 0

        for j in n:
            if (i % 2 == 0):
                x = n[i]
                y = n[i + 1]

                # String containing the co-ordinates.
                string = str(x) + " " + str(y)

                if (i == 0):
                    # text on topmost co-ordinate.
                    cv2.putText(frame, "Arrow tip", (x, y),
                                font, 0.5, (255, 0, 0))
                else:
                    # text on remaining co-ordinates.
                    cv2.putText(frame, string, (x, y),
                                font, 0.5, (0, 255, 0))
            i += 1

    #cv2.imshow("frame", frame)
    #cv2.imshow("mask", mask)
    cv2.imshow("res", res)
    cv2.imshow("bin", bin)

    key = cv2.waitKey(1)
    if key == 27:
        break

cv2.destroyAllWindows()

有人可以帮我解决这个问题，非常感谢！

Answer 1

问题是您没有将灰色图像传递给findCountours，这是必需的。要解决它，必须在bitwise_and操作之后将res转换为灰度：

<!-- language: python -->
gray = cv2.cvtColor(res, cv2.COLOR_BGR2GRAY)
trash, bin = cv2.threshold(gray, 227, 255, 1, cv2.THRESH_BINARY)

完整代码：

import cv2
import numpy as np


def nothing(x):
    pass


cv2.namedWindow("Tracking")
cv2.createTrackbar("LH", "Tracking", 0, 255, nothing)
cv2.createTrackbar("LS", "Tracking", 0, 255, nothing)
cv2.createTrackbar("LV", "Tracking", 0, 255, nothing)
cv2.createTrackbar("UH", "Tracking", 255, 255, nothing)
cv2.createTrackbar("US", "Tracking", 255, 255, nothing)
cv2.createTrackbar("UV", "Tracking", 255, 255, nothing)

while True:
    frame = cv2.imread('3Blobs.jpg', 1)
    font = cv2.FONT_HERSHEY_COMPLEX
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

    l_h = cv2.getTrackbarPos("LH", "Tracking")
    l_s = cv2.getTrackbarPos("LS", "Tracking")
    l_v = cv2.getTrackbarPos("LV", "Tracking")

    u_h = cv2.getTrackbarPos("UH", "Tracking")
    u_s = cv2.getTrackbarPos("US", "Tracking")
    u_v = cv2.getTrackbarPos("UV", "Tracking")

    l_b = np.array([l_h, l_s, l_v])
    u_b = np.array([u_h, u_s, u_v])

    mask = cv2.inRange(hsv, l_b, u_b)

    res = cv2.bitwise_and(frame, frame, mask=mask)
    gray = cv2.cvtColor(res, cv2.COLOR_BGR2GRAY)
    trash, bin = cv2.threshold(gray, 227, 255, 1, cv2.THRESH_BINARY)

    # Detecting contours in image.
    contours, _ = cv2.findContours(bin, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

    # Going through every contours found in the image.
    for cnt in contours:

        approx = cv2.approxPolyDP(cnt, 0.009 * cv2.arcLength(cnt, True), True)

        # draws boundary of contours.
        cv2.drawContours(frame, [approx], 0, (0, 0, 255), 2)

        # Used to flatted the array containing
        # the co-ordinates of the vertices.
        n = approx.ravel()
        i = 0

        for j in n:
            if (i % 2 == 0):
                x = n[i]
                y = n[i + 1]

                # String containing the co-ordinates.
                string = str(x) + " " + str(y)

                if (i == 0):
                    # text on topmost co-ordinate.
                    cv2.putText(frame, "Arrow tip", (x, y),
                                font, 0.5, (255, 0, 0))
                else:
                    # text on remaining co-ordinates.
                    cv2.putText(frame, string, (x, y),
                                font, 0.5, (0, 255, 0))
            i += 1

    # cv2.imshow("frame", frame)
    # cv2.imshow("mask", mask)

    cv2.namedWindow('res', cv2.WINDOW_NORMAL)
    cv2.namedWindow('bin', cv2.WINDOW_NORMAL)
    cv2.imshow("res", res)
    cv2.imshow("bin", bin)

    key = cv2.waitKey(1)
    if key == 27:
        break

cv2.destroyAllWindows()

结果：