OpenCV waitKey in python doesn't work on mac

I'm writing code to face recognition in python and i'm using open cv on mac (PyCharm).
I don't understand why:

            if cv2.waitKey(1) & 0xFF == ord('q'):

                break

doesn't work on mac, but on windows this code work.
In particular q doesn't trigger the if.

I try to change with:
k = cv2.waitKey(0)
if k == 27:
break

Below write my code

def run(self):

    video_capture = cv2.VideoCapture(0)

    try:

        while self.active:

            # Grab a single frame of video

            ret, frame = video_capture.read()



            # Convert the image from BGR color (which OpenCV uses) to RGB color (which face_recognition uses)

            rgb_frame = frame[:, :, ::-1]



            # Find all the faces and face enqcodings in the frame of video

            face_locations = face_recognition.face_locations(rgb_frame)

            face_encodings = face_recognition.face_encodings(rgb_frame, face_locations)



            # Loop through each face in this frame of video

            for (top, right, bottom, left), face_encoding in zip(face_locations, face_encodings):

                # See if the face is a match for the known face(s)

                matches = face_recognition.compare_faces(self.known_face_encodings, face_encoding)



                name = "Unknown"



                # If a match was found in known_face_encodings, just use the first one.

                if True in matches:

                    first_match_index = matches.index(True)

                    name = self.known_face_names[first_match_index]



                # Draw a box around the face

                cv2.rectangle(frame, (left, top), (right, bottom), (0, 0, 255), 2)



                # Draw a label with a name below the face

                cv2.rectangle(frame, (left, bottom - 35), (right, bottom), (0, 0, 255), cv2.FILLED)

                font = cv2.FONT_HERSHEY_DUPLEX

                cv2.putText(frame, name, (left + 6, bottom - 6), font, 1.0, (255, 255, 255), 1)

                if (name != "Unknown"):

                    self.reco.emit(name)

                    self.deactivate()

                    video_capture.release()

                    cv2.destroyAllWindows()

                else:

                    self.unreco.emit()

                    self.deactivate()

                    video_capture.release()

                    cv2.destroyAllWindows()

            # Display the resulting image

            # cv2.imshow('Video', frame)

            # Hit 'q' on the keyboard to quit!

            if cv2.waitKey(1) & 0xFF == ord('q'):

                break

    except:

        print("error while recognize")

edited Jan 20 at 15:27

asked Jan 20 at 15:12

Alessandro Minervini

could you be a little more specific? what does doesn't work mean? do you get an error? does q not trigger the if? did you try clicking the opencv window and then hitting q?

– Nullman
Jan 20 at 15:13

if i press q, q not trigger the if

– Alessandro Minervini
Jan 20 at 15:24

OK, so did you inspect the return value from cv2.waitKey to see what it actually returns when you press q? Is there a window present? (I see the only imshow commented out -- perhaps it needs a window to be able to capture keyboard events?)

– Dan Mašek
Jan 20 at 17:22

Returns -1 before i type from the keyboard, (for the window there's video_capture.read() i think)

– Alessandro Minervini
Jan 20 at 17:31

Isn't PyCharm some dev environment? Maybe it grabs keyboard input. Try running outside of PyCharm, maybe.

– Mark Setchell
Jan 20 at 17:48

|
show 1 more comment

I'm writing code to face recognition in python and i'm using open cv on mac (PyCharm).
I don't understand why:

            if cv2.waitKey(1) & 0xFF == ord('q'):

                break

doesn't work on mac, but on windows this code work.
In particular q doesn't trigger the if.

I try to change with:
k = cv2.waitKey(0)
if k == 27:
break

Below write my code

def run(self):

    video_capture = cv2.VideoCapture(0)

    try:

        while self.active:

            # Grab a single frame of video

            ret, frame = video_capture.read()



            # Convert the image from BGR color (which OpenCV uses) to RGB color (which face_recognition uses)

            rgb_frame = frame[:, :, ::-1]



            # Find all the faces and face enqcodings in the frame of video

            face_locations = face_recognition.face_locations(rgb_frame)

            face_encodings = face_recognition.face_encodings(rgb_frame, face_locations)



            # Loop through each face in this frame of video

            for (top, right, bottom, left), face_encoding in zip(face_locations, face_encodings):

                # See if the face is a match for the known face(s)

                matches = face_recognition.compare_faces(self.known_face_encodings, face_encoding)



                name = "Unknown"



                # If a match was found in known_face_encodings, just use the first one.

                if True in matches:

                    first_match_index = matches.index(True)

                    name = self.known_face_names[first_match_index]



                # Draw a box around the face

                cv2.rectangle(frame, (left, top), (right, bottom), (0, 0, 255), 2)



                # Draw a label with a name below the face

                cv2.rectangle(frame, (left, bottom - 35), (right, bottom), (0, 0, 255), cv2.FILLED)

                font = cv2.FONT_HERSHEY_DUPLEX

                cv2.putText(frame, name, (left + 6, bottom - 6), font, 1.0, (255, 255, 255), 1)

                if (name != "Unknown"):

                    self.reco.emit(name)

                    self.deactivate()

                    video_capture.release()

                    cv2.destroyAllWindows()

                else:

                    self.unreco.emit()

                    self.deactivate()

                    video_capture.release()

                    cv2.destroyAllWindows()

            # Display the resulting image

            # cv2.imshow('Video', frame)

            # Hit 'q' on the keyboard to quit!

            if cv2.waitKey(1) & 0xFF == ord('q'):

                break

    except:

        print("error while recognize")

edited Jan 20 at 15:27

asked Jan 20 at 15:12

Alessandro Minervini

could you be a little more specific? what does doesn't work mean? do you get an error? does q not trigger the if? did you try clicking the opencv window and then hitting q?

– Nullman
Jan 20 at 15:13

if i press q, q not trigger the if

– Alessandro Minervini
Jan 20 at 15:24

OK, so did you inspect the return value from cv2.waitKey to see what it actually returns when you press q? Is there a window present? (I see the only imshow commented out -- perhaps it needs a window to be able to capture keyboard events?)

– Dan Mašek
Jan 20 at 17:22

Returns -1 before i type from the keyboard, (for the window there's video_capture.read() i think)

– Alessandro Minervini
Jan 20 at 17:31

Isn't PyCharm some dev environment? Maybe it grabs keyboard input. Try running outside of PyCharm, maybe.

– Mark Setchell
Jan 20 at 17:48

|
show 1 more comment

I'm writing code to face recognition in python and i'm using open cv on mac (PyCharm).
I don't understand why:

            if cv2.waitKey(1) & 0xFF == ord('q'):

                break

doesn't work on mac, but on windows this code work.
In particular q doesn't trigger the if.

I try to change with:
k = cv2.waitKey(0)
if k == 27:
break

Below write my code

def run(self):

    video_capture = cv2.VideoCapture(0)

    try:

        while self.active:

            # Grab a single frame of video

            ret, frame = video_capture.read()



            # Convert the image from BGR color (which OpenCV uses) to RGB color (which face_recognition uses)

            rgb_frame = frame[:, :, ::-1]



            # Find all the faces and face enqcodings in the frame of video

            face_locations = face_recognition.face_locations(rgb_frame)

            face_encodings = face_recognition.face_encodings(rgb_frame, face_locations)



            # Loop through each face in this frame of video

            for (top, right, bottom, left), face_encoding in zip(face_locations, face_encodings):

                # See if the face is a match for the known face(s)

                matches = face_recognition.compare_faces(self.known_face_encodings, face_encoding)



                name = "Unknown"



                # If a match was found in known_face_encodings, just use the first one.

                if True in matches:

                    first_match_index = matches.index(True)

                    name = self.known_face_names[first_match_index]



                # Draw a box around the face

                cv2.rectangle(frame, (left, top), (right, bottom), (0, 0, 255), 2)



                # Draw a label with a name below the face

                cv2.rectangle(frame, (left, bottom - 35), (right, bottom), (0, 0, 255), cv2.FILLED)

                font = cv2.FONT_HERSHEY_DUPLEX

                cv2.putText(frame, name, (left + 6, bottom - 6), font, 1.0, (255, 255, 255), 1)

                if (name != "Unknown"):

                    self.reco.emit(name)

                    self.deactivate()

                    video_capture.release()

                    cv2.destroyAllWindows()

                else:

                    self.unreco.emit()

                    self.deactivate()

                    video_capture.release()

                    cv2.destroyAllWindows()

            # Display the resulting image

            # cv2.imshow('Video', frame)

            # Hit 'q' on the keyboard to quit!

            if cv2.waitKey(1) & 0xFF == ord('q'):

                break

    except:

        print("error while recognize")

edited Jan 20 at 15:27

asked Jan 20 at 15:12

Alessandro Minervini

I'm writing code to face recognition in python and i'm using open cv on mac (PyCharm).
I don't understand why:

            if cv2.waitKey(1) & 0xFF == ord('q'):

                break

doesn't work on mac, but on windows this code work.
In particular q doesn't trigger the if.

I try to change with:
k = cv2.waitKey(0)
if k == 27:
break

Below write my code

def run(self):

    video_capture = cv2.VideoCapture(0)

    try:

        while self.active:

            # Grab a single frame of video

            ret, frame = video_capture.read()



            # Convert the image from BGR color (which OpenCV uses) to RGB color (which face_recognition uses)

            rgb_frame = frame[:, :, ::-1]



            # Find all the faces and face enqcodings in the frame of video

            face_locations = face_recognition.face_locations(rgb_frame)

            face_encodings = face_recognition.face_encodings(rgb_frame, face_locations)



            # Loop through each face in this frame of video

            for (top, right, bottom, left), face_encoding in zip(face_locations, face_encodings):

                # See if the face is a match for the known face(s)

                matches = face_recognition.compare_faces(self.known_face_encodings, face_encoding)



                name = "Unknown"



                # If a match was found in known_face_encodings, just use the first one.

                if True in matches:

                    first_match_index = matches.index(True)

                    name = self.known_face_names[first_match_index]



                # Draw a box around the face

                cv2.rectangle(frame, (left, top), (right, bottom), (0, 0, 255), 2)



                # Draw a label with a name below the face

                cv2.rectangle(frame, (left, bottom - 35), (right, bottom), (0, 0, 255), cv2.FILLED)

                font = cv2.FONT_HERSHEY_DUPLEX

                cv2.putText(frame, name, (left + 6, bottom - 6), font, 1.0, (255, 255, 255), 1)

                if (name != "Unknown"):

                    self.reco.emit(name)

                    self.deactivate()

                    video_capture.release()

                    cv2.destroyAllWindows()

                else:

                    self.unreco.emit()

                    self.deactivate()

                    video_capture.release()

                    cv2.destroyAllWindows()

            # Display the resulting image

            # cv2.imshow('Video', frame)

            # Hit 'q' on the keyboard to quit!

            if cv2.waitKey(1) & 0xFF == ord('q'):

                break

    except:

        print("error while recognize")

python opencv cv2

edited Jan 20 at 15:27

asked Jan 20 at 15:12

Alessandro Minervini

edited Jan 20 at 15:27

asked Jan 20 at 15:12

Alessandro Minervini

edited Jan 20 at 15:27

asked Jan 20 at 15:12

Alessandro Minervini

asked Jan 20 at 15:12

Alessandro Minervini

asked Jan 20 at 15:12

Alessandro Minervini

could you be a little more specific? what does doesn't work mean? do you get an error? does q not trigger the if? did you try clicking the opencv window and then hitting q?

– Nullman
Jan 20 at 15:13

if i press q, q not trigger the if

– Alessandro Minervini
Jan 20 at 15:24

OK, so did you inspect the return value from cv2.waitKey to see what it actually returns when you press q? Is there a window present? (I see the only imshow commented out -- perhaps it needs a window to be able to capture keyboard events?)

– Dan Mašek
Jan 20 at 17:22

Returns -1 before i type from the keyboard, (for the window there's video_capture.read() i think)

– Alessandro Minervini
Jan 20 at 17:31

Isn't PyCharm some dev environment? Maybe it grabs keyboard input. Try running outside of PyCharm, maybe.

– Mark Setchell
Jan 20 at 17:48

|
show 1 more comment

could you be a little more specific? what does doesn't work mean? do you get an error? does q not trigger the if? did you try clicking the opencv window and then hitting q?

– Nullman
Jan 20 at 15:13

if i press q, q not trigger the if

– Alessandro Minervini
Jan 20 at 15:24

OK, so did you inspect the return value from cv2.waitKey to see what it actually returns when you press q? Is there a window present? (I see the only imshow commented out -- perhaps it needs a window to be able to capture keyboard events?)

– Dan Mašek
Jan 20 at 17:22

Returns -1 before i type from the keyboard, (for the window there's video_capture.read() i think)

– Alessandro Minervini
Jan 20 at 17:31

Isn't PyCharm some dev environment? Maybe it grabs keyboard input. Try running outside of PyCharm, maybe.

– Mark Setchell
Jan 20 at 17:48

could you be a little more specific? what does doesn't work mean? do you get an error? does q not trigger the if? did you try clicking the opencv window and then hitting q?

– Nullman
Jan 20 at 15:13

if i press q, q not trigger the if

– Alessandro Minervini
Jan 20 at 15:24

OK, so did you inspect the return value from cv2.waitKey to see what it actually returns when you press q? Is there a window present? (I see the only imshow commented out -- perhaps it needs a window to be able to capture keyboard events?)

– Dan Mašek
Jan 20 at 17:22

Returns -1 before i type from the keyboard, (for the window there's video_capture.read() i think)

– Alessandro Minervini
Jan 20 at 17:31

Isn't PyCharm some dev environment? Maybe it grabs keyboard input. Try running outside of PyCharm, maybe.

– Mark Setchell
Jan 20 at 17:48

|
show 1 more comment

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