Python face detection not working in terminal

Question

I am trying to make a face detection python programme using opencv but when i run the following shell command I get the following error:

when i typed: python main2.py abba.png haarcascade_frontalface_default.xml

I am using opencv and I used the following documentationRealpython face Recognition:

(venv) C:\Users\User\PycharmProjects\main_1>python face_detect.py abba.png haarcascade_frontalface_default.xml
C:\Users\User\AppData\Local\Programs\Python\Python39\python.exe: can't open file 'C:\Users\User\PycharmProjects\main_1\face_detect.py': [Errno 2] No such file or directory

(venv) C:\Users\User\PycharmProjects\main_1>python main2.py abba.png haarcascade_frontalface_default.xml
Traceback (most recent call last):
  File "C:\Users\User\PycharmProjects\main_1\main2.py", line 13, in <module>
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(4.4.0) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-95hbg2jt\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src
.empty() in function 'cv::cvtColor'

Here is the Code I used:

import sys
import cv2

# Get user supplied values
imagePath = sys.argv[1]
cascPath = sys.argv[2]

# Create the haar cascade
faceCascade = cv2.CascadeClassifier(cascPath)

# Read the image
image = cv2.imread(imagePath)
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)

# Detect faces in the image
faces = faceCascade.detectMultiScale(
    gray,
    scaleFactor=1.1,
    minNeighbors=5,
    minSize=(30, 30),
    flags=cv2.cv.CV_HAAR_SCALE_IMAGE
)

print("Found {0} faces!".format(len(faces)))

# Draw a rectangle around the faces
for (x, y, w, h) in faces:
    cv2.rectangle(image, (x, y), (x+w, y+h), (0, 255, 0), 2)

cv2.imshow("Faces found", image)
cv2.waitKey(0)

Answer 1

This error indicates that the image file wasn't found correctly:

C:\Users\User\AppData\Local\Programs\Python\Python39\python.exe: can't open file 'C:\Users\User\PycharmProjects\main_1\face_detect.py': [Errno 2] No such file or directory

And thus it can't convert color using opencv of something (image) that's not a valid file.

File "C:\Users\User\PycharmProjects\main_1\main2.py", line 13, in <module>
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(4.4.0) C:\Users\appveyor\AppData\Local\Temp\1\pip-req-build-95hbg2jt\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src
.empty() in function 'cv::cvtColor'

So, check if your folder contains the file you want to use, in your case: abba.png.

Use the command dir to list all the directories and files in a directory using windows cmd; ls is a unix command.