drawCountour()不起作用

Question

视频帧中drawContour()功能不正常。它通过使用这个堆栈溢出答案来处理图像。输出的是没有任何轮廓的清晰图像。

下面是我的代码:

import cv2
import numpy as np
cap = cv2.VideoCapture(0)
while True:
    _, frame = cap.read()
    ret,thresh1 = cv2.threshold(frame,127,255,cv2.THRESH_BINARY)
    kernel = np.ones((5,5),np.uint8)
    erosion = cv2.erode(thresh1,kernel,iterations = 1)

    edges = cv2.Canny(erosion, 100 ,200)
    imCopy = edges.copy()
    laplacian = cv2.Laplacian(edges, cv2.CV_8UC1)
    sobely = cv2.Sobel(laplacian,cv2.CV_8UC1, 0, 1, ksize=5)
    im2, contours, hierarchy = cv2.findContours(sobely,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
    frame = cv2.drawContours(im2, contours, -1, (255,0,0), 3)
    cv2.imshow('window',frame)
    print len(contours)
    k = cv2.waitKey(5) & 0xFF
    if k==27:
       break
cv2.destroyAllWindows()
cap.release()

Answer 1

绘制的轮廓不会着色，因为您是在单通道图像上绘制它们。这里是如何绘制彩色的。(假设frame = BGR。如果原来的frame是灰度，使用cvtColor将下面代码中的frame_copy转换为BGR)。

_, frame = cap.read()
frame_copy = np.copy(frame)
.
.
.
cv2.drawContours(frame_copy, contours, -1, (255,0,0), 3)
cv2.imshow('window',frame_copy)

Answer 2

use

frame = cv2.drawContours(frame, contours, -1, (255,0,0), 3)
cv2.imshow('window',frame)