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 select 想要的颜色，然后用它的 x 和 y 坐标获得轮廓。当我运行代码时，我得到下一个错误： 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()

谁能帮我解决这个问题，非常感谢！

Answer 1

问题是您没有将灰度图像传递给 findCountours，这是必需的。要解决它，必须将bitwise_and操作后的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：

使用轨迹栏检测颜色并找到所需颜色的轮廓

Detection of color with a trackbar and finding the contour of the desired color

opencv

opencv-contour

opencv-drawcontour