I'm using windows7 and Pycharm 2019.3 with Python 3, Can't find the solution to cvtColor command in the code below:

Question

The error that arises is:

cv2.error: OpenCV(4.0.0) c:\projects\opencv-python\opencv\modules\imgproc\src\color.hpp:259: error: (-2:Unspecified error) in function '__cdecl cv::CvtHelper<struct cv::Set<3,4,-1>,struct cv::Set<1,-1,-1>,struct cv::Set<0,2,5>,2>::CvtHelper(const class cv::_InputArray &,const class cv::_OutputArray &,int)'
> Invalid number of channels in input image:
>     'VScn::contains(scn)'

Where scn is 1.

Please help me:

import cv2
import numpy as np

img = r'C:\Users\Vinay\Desktop\picture.jpg'

eye_cascade = cv2.CascadeClassifier('C:/Python/tutorial/Classifiers/haarscascade_eye.xml')

img = cv2.imread(img,0)
cv2.imshow('image',img)
cv2.waitKey(500)

img2=cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

cv2.CascadeClassifier.detectMultiScale(cv2.CascadeClassifier('C:/Python/tutorial/Classifiers/haarscascade_eye.xml'), img, 1.3, 5)
eyes = eye_cascade.detectMultiScale(img, 1.3, 5)
for (x, y, w, h) in eyes:
    cv2.rectangle(img, (x,y), (x+w, y+h), (0,255,0),2)

cv2.imshow('image', img)
cv2.waitKey(5000)
cv2.destroyAllWindows()

Answer 1

While reading the image you have specified imread(img, 0) which means the image will be automatically be read in Grayscale so there is no need to convert it to gray using cvtColor .

However if you want to access it as a colored image somewhere make the imread line as imread(img) and convert it to grayscale using cvtColor .