Question

我在RaspberryPi中使用opencv 3.1 3.我试图运行以下Hough Circle检测算法

#! /usr/bin/python
import numpy as np
import cv2
from cv2 import cv

VInstance = cv2.VideoCapture(0)
key = True


"""
params = dict(dp,
              minDist,
              circles,
              param1,
              param2,
              minRadius,
              maxRadius)
"""
def draw_circles(circles, output):

    if circles is not None:

        for i in circles[0,:]:
            #draw the outer circle
            cv2.circle(output,(i[0],i[1]),i[2],(0,255,0),2)
            #draw the centre of the circle
            cv2.circle(output,(i[0],i[1]),2,(0,0,255),3)
            print("The number of circles if %d" %(circles[0].shape[0]))      
    elif circles is None:
        print ("The number of circles is 0")

if __name__ == '__main__':

    while key:
        ret,img = VInstance.read()
        ## Smooth image to reduce the input noise

        imgGray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
        imgSmooth = cv2.GaussianBlur(imgGray,(5,5),3)

        ## Compute Hough Circles
        circles = cv2.HoughCircles(imgSmooth,cv2.cv.CV_HOUGH_GRADIENT,1,100,
                                   param1=80,
                                   param2=50,
                                   minRadius=50,
                                   maxRadius=100)
        draw_circles(circles,img)

        ## Display the circles
        cv2.imshow('detected circles',imgGray)
        cv2.imshow("result",img)
        k = cv2.waitKey(1)
        if k == 27:
            cv2.destroyAllWindows()
            break

但我收到Assertion Failed错误，详情如下。

OpenCV错误：cvtColor中的断言失败（scn == 3 || scn == 4），文件/home/pi/opencv-3.1.0/modules/imgproc/src/color.cpp，第8000行回溯（最近一次调用最后一次）：文件＆＃34; HoughCircles.py＆＃34;，第70行，在 imgGray = cv2.cvtColor（img，cv2.COLOR_BGR2GRAY）cv2.error：/home/pi/opencv-3.1.0/modules/imgproc/src/color.cpp:8000：错误：（-215）scn == 3 || scn == 4 in function cvtColor

任何人都可以查看并提供帮助！

Answer 1

错误代码＆＃34;断言失败（scn == 3 || scn == 4）在cvtColor＆＃34;表示public class CompositeProduct` extends Product { private List<Product> products; public CompositeProduct(List<Product> products) { this.products = products } public String preview() { String previewText = ""; for(Product product : products) { previewText+=product.preview(); } return preview; } }方法中的输入（源）图像没有3或4个通道，这是此类转换所必需的。可能您的输入图像已经是灰度格式。尽量不要使用该方法，您的问题应该得到解决。如果它确实抛出其他无法解决的错误或无法解决问题，请在评论中发布您的问题。

Answer 2

这意味着输入图像无效，这就是您需要检查循环中ret值的原因！

错误和问题标题与你的Hough圈没有任何关系，所以我会压缩我的答案以解决断言失败（稍后再加入你的东西！）：

#!/usr/bin/python
import numpy as np
import cv2

VInstance = cv2.VideoCapture(0)

if __name__ == '__main__':

    while True:
        ret,img = VInstance.read()

        # Confirm we have a valid image returned
        if not ret:
            break

        imgGray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)

        cv2.imshow("result",img)

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

    cv2.destroyAllWindows()

获取openCV错误：断言失败

2 个答案: