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0

How to fix error when try to convert frame into grayscale?

Error message: cv2.cvtColor(image, cv2.COLOR_BGR2GRAY) cv2.error: OpenCV(4.0.0) c:projectsopencv-pythonopencvmodulesimgprocsrccolor.hpp:259: error: (-2:Unspecified error) in function '__cdecl cv::CvtHelper,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

class OpenCVCapture(object):
def __init__(self, device_id=0):
 """Create an OpenCV capture object associated with the provided webcam
 device ID.
 """
 # Open the camera.
 self._camera = cv2.VideoCapture(device_id)
 if not self._camera.isOpened():
 self._camera.open()
 # Start a thread to continuously capture frames.
 # This must be done because different layers of buffering in the webcam
 # and OS drivers will cause you to retrieve old frames if they aren't 
 # continuously read.
 self._capture_frame = None
 # Use a lock to prevent access concurrent access to the camera.
 self._capture_lock = threading.Lock()
 self._capture_thread = threading.Thread(target=self._grab_frames)
 self._capture_thread.daemon = True
 self._capture_thread.start()

def _grab_frames(self):
 while True:
 retval, frame = self._camera.read()
 frame = cv2.cvtColor(frame, cv2.COLOR_RGB2GRAY)
 with self._capture_lock:
 self._capture_frame = None
 if retval:
 self._capture_frame = frame
 time.sleep(1.0/CAPTURE_HZ)

def read(self):
 """Read a single frame from the camera and return the data as an OpenCV
 image (which is a numpy array).
 """
 frame = None
 with self._capture_lock:
 frame = self._capture_frame

 # If there are problems, keep retrying until an image can be read.
 while frame is None:
 time.sleep(0)
 with self._capture_lock:
 frame = self._capture_frame
 # Save captured image for debugging.
 cv2.imwrite(config.DEBUG_IMAGE, frame)
 # Return the capture image data.
 return frame

python python-3.x opencv cv2 opencv4

share|improve this question

edited Mar 24 at 12:03

Nicholas Chuah

asked Mar 24 at 11:13

Nicholas ChuahNicholas Chuah

45

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Please, provide frame.shape and frame.dtype
  
  – Berriel
  Mar 24 at 11:15
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You might want to proof-read your post (especially title) -- imwrite (as the name would suggest) isn't used for reading... | Also add a proper minimal reproducible example -- right now you claim you "feed in grayscale image"... but how do we know that's actually the case?
  
  – Dan Mašek
  Mar 24 at 11:19
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @DanMašek i added in code which i turn the image frame into grayscale, thanks for the correction
  
  – Nicholas Chuah
  Mar 24 at 11:34
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Berriel the shape is (480, 640, 3) and dtype uint8
  
  – Nicholas Chuah
  Mar 24 at 11:39
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Given that the 3rd value of shape (the number of channels) is 3, it's definitely not a grayscale image at that point... which seems rather odd given that code.
  
  – Dan Mašek
  Mar 24 at 11:42
  
  

  
  
  
  

 | 
show 5 more comments

0

How to fix error when try to convert frame into grayscale?

Error message: cv2.cvtColor(image, cv2.COLOR_BGR2GRAY) cv2.error: OpenCV(4.0.0) c:projectsopencv-pythonopencvmodulesimgprocsrccolor.hpp:259: error: (-2:Unspecified error) in function '__cdecl cv::CvtHelper,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

class OpenCVCapture(object):
def __init__(self, device_id=0):
 """Create an OpenCV capture object associated with the provided webcam
 device ID.
 """
 # Open the camera.
 self._camera = cv2.VideoCapture(device_id)
 if not self._camera.isOpened():
 self._camera.open()
 # Start a thread to continuously capture frames.
 # This must be done because different layers of buffering in the webcam
 # and OS drivers will cause you to retrieve old frames if they aren't 
 # continuously read.
 self._capture_frame = None
 # Use a lock to prevent access concurrent access to the camera.
 self._capture_lock = threading.Lock()
 self._capture_thread = threading.Thread(target=self._grab_frames)
 self._capture_thread.daemon = True
 self._capture_thread.start()

def _grab_frames(self):
 while True:
 retval, frame = self._camera.read()
 frame = cv2.cvtColor(frame, cv2.COLOR_RGB2GRAY)
 with self._capture_lock:
 self._capture_frame = None
 if retval:
 self._capture_frame = frame
 time.sleep(1.0/CAPTURE_HZ)

def read(self):
 """Read a single frame from the camera and return the data as an OpenCV
 image (which is a numpy array).
 """
 frame = None
 with self._capture_lock:
 frame = self._capture_frame

 # If there are problems, keep retrying until an image can be read.
 while frame is None:
 time.sleep(0)
 with self._capture_lock:
 frame = self._capture_frame
 # Save captured image for debugging.
 cv2.imwrite(config.DEBUG_IMAGE, frame)
 # Return the capture image data.
 return frame

python python-3.x opencv cv2 opencv4

share|improve this question

edited Mar 24 at 12:03

Nicholas Chuah

asked Mar 24 at 11:13

Nicholas ChuahNicholas Chuah

45

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Please, provide frame.shape and frame.dtype
  
  – Berriel
  Mar 24 at 11:15
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You might want to proof-read your post (especially title) -- imwrite (as the name would suggest) isn't used for reading... | Also add a proper minimal reproducible example -- right now you claim you "feed in grayscale image"... but how do we know that's actually the case?
  
  – Dan Mašek
  Mar 24 at 11:19
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @DanMašek i added in code which i turn the image frame into grayscale, thanks for the correction
  
  – Nicholas Chuah
  Mar 24 at 11:34
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @Berriel the shape is (480, 640, 3) and dtype uint8
  
  – Nicholas Chuah
  Mar 24 at 11:39
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Given that the 3rd value of shape (the number of channels) is 3, it's definitely not a grayscale image at that point... which seems rather odd given that code.
  
  – Dan Mašek
  Mar 24 at 11:42
  
  

  
  
  
  

 | 
show 5 more comments

How to fix error when try to convert frame into grayscale?

Error message: cv2.cvtColor(image, cv2.COLOR_BGR2GRAY) cv2.error: OpenCV(4.0.0) c:projectsopencv-pythonopencvmodulesimgprocsrccolor.hpp:259: error: (-2:Unspecified error) in function '__cdecl cv::CvtHelper,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

class OpenCVCapture(object):
def __init__(self, device_id=0):
 """Create an OpenCV capture object associated with the provided webcam
 device ID.
 """
 # Open the camera.
 self._camera = cv2.VideoCapture(device_id)
 if not self._camera.isOpened():
 self._camera.open()
 # Start a thread to continuously capture frames.
 # This must be done because different layers of buffering in the webcam
 # and OS drivers will cause you to retrieve old frames if they aren't 
 # continuously read.
 self._capture_frame = None
 # Use a lock to prevent access concurrent access to the camera.
 self._capture_lock = threading.Lock()
 self._capture_thread = threading.Thread(target=self._grab_frames)
 self._capture_thread.daemon = True
 self._capture_thread.start()

def _grab_frames(self):
 while True:
 retval, frame = self._camera.read()
 frame = cv2.cvtColor(frame, cv2.COLOR_RGB2GRAY)
 with self._capture_lock:
 self._capture_frame = None
 if retval:
 self._capture_frame = frame
 time.sleep(1.0/CAPTURE_HZ)

def read(self):
 """Read a single frame from the camera and return the data as an OpenCV
 image (which is a numpy array).
 """
 frame = None
 with self._capture_lock:
 frame = self._capture_frame

 # If there are problems, keep retrying until an image can be read.
 while frame is None:
 time.sleep(0)
 with self._capture_lock:
 frame = self._capture_frame
 # Save captured image for debugging.
 cv2.imwrite(config.DEBUG_IMAGE, frame)
 # Return the capture image data.
 return frame

python python-3.x opencv cv2 opencv4

share|improve this question

edited Mar 24 at 12:03

Nicholas Chuah

asked Mar 24 at 11:13

Nicholas ChuahNicholas Chuah

45

class OpenCVCapture(object):
def __init__(self, device_id=0):
 """Create an OpenCV capture object associated with the provided webcam
 device ID.
 """
 # Open the camera.
 self._camera = cv2.VideoCapture(device_id)
 if not self._camera.isOpened():
 self._camera.open()
 # Start a thread to continuously capture frames.
 # This must be done because different layers of buffering in the webcam
 # and OS drivers will cause you to retrieve old frames if they aren't 
 # continuously read.
 self._capture_frame = None
 # Use a lock to prevent access concurrent access to the camera.
 self._capture_lock = threading.Lock()
 self._capture_thread = threading.Thread(target=self._grab_frames)
 self._capture_thread.daemon = True
 self._capture_thread.start()

def _grab_frames(self):
 while True:
 retval, frame = self._camera.read()
 frame = cv2.cvtColor(frame, cv2.COLOR_RGB2GRAY)
 with self._capture_lock:
 self._capture_frame = None
 if retval:
 self._capture_frame = frame
 time.sleep(1.0/CAPTURE_HZ)

def read(self):
 """Read a single frame from the camera and return the data as an OpenCV
 image (which is a numpy array).
 """
 frame = None
 with self._capture_lock:
 frame = self._capture_frame

 # If there are problems, keep retrying until an image can be read.
 while frame is None:
 time.sleep(0)
 with self._capture_lock:
 frame = self._capture_frame
 # Save captured image for debugging.
 cv2.imwrite(config.DEBUG_IMAGE, frame)
 # Return the capture image data.
 return frame

share|improve this question

edited Mar 24 at 12:03

Nicholas Chuah

asked Mar 24 at 11:13

Nicholas ChuahNicholas Chuah

45

share|improve this question

edited Mar 24 at 12:03

Nicholas Chuah

asked Mar 24 at 11:13

Nicholas ChuahNicholas Chuah

45

asked Mar 24 at 11:13

Nicholas ChuahNicholas Chuah

45

asked Mar 24 at 11:13

Nicholas ChuahNicholas Chuah

45