Unable to save image from Raspi camera -> cv2.imwrite (Using Jetson Nano)

Question

I am trying to save images from the Raspi cameras connected to my Jetson nano. My Code is below. However, the code shows that it is saving the files, but no matter which method I try I cannot find the images. Thanks for your help. I've included a smaller snippet of just the while loop itself so it will be easier for you all to refer to.

While loop:

while True:
            
            _ , left_image=left_camera.read()
            _ , right_image=right_camera.read()
            camera_images = np.hstack((left_image, right_image))
            cv2.imshow("CSI Cameras", camera_images)
            
    
    
            t1 = datetime.now()
            cntdwn_timer = countdown - int ((t1-t2).total_seconds())
            # If cowntdown is zero - let's record next image
            if cntdwn_timer == -1:
                counter += 1
    
                filename = './scenes/scene_'+ str(counter) + 'x'+'_'+ '.png'
                #img = cv2.imread(camera_images)
                #cv2.imwrite(os.path.join(os.path.expanduser('~'),'CSI-Camera', filename), camera_images)
                cv2.imwrite('/home/aryan/CSI-Camera/{}'.format(filename), camera_images)
                print (' monkey'+filename)
                t2 = datetime.now()
                time.sleep(1)
                cntdwn_timer = 0      # To avoid "-1" timer display 
                next
            
    
            # This also acts as
            keyCode = cv2.waitKey(30) & 0xFF
            # Stop the program on the ESC key
            if keyCode == 27:
                break
    
        left_camera.stop()
        left_camera.release()
        right_camera.stop()
        right_camera.release()
        cv2.destroyAllWindows()
    

 

import cv2
import threading
import numpy as np
import time
from datetime import datetime

# gstreamer_pipeline returns a GStreamer pipeline for capturing from the CSI camera
# Flip the image by setting the flip_method (most common values: 0 and 2)
# display_width and display_height determine the size of each camera pane in the window on the screen

left_camera = None
right_camera = None

#PiCam
# Photo session settings
total_photos = 30             # Number of images to take
countdown = 5                 # Interval for count-down timer, seconds
font=cv2.FONT_HERSHEY_SIMPLEX # Cowntdown timer font


class CSI_Camera:

    def __init__ (self) :
        # Initialize instance variables
        # OpenCV video capture element
        self.video_capture = None
        # The last captured image from the camera
        self.frame = None
        self.grabbed = False
        # The thread where the video capture runs
        self.read_thread = None
        self.read_lock = threading.Lock()
        self.running = False


    def open(self, gstreamer_pipeline_string):
        try:
            self.video_capture = cv2.VideoCapture(
                gstreamer_pipeline_string, cv2.CAP_GSTREAMER
            )
            
        except RuntimeError:
            self.video_capture = None
            print("Unable to open camera")
            print("Pipeline: " + gstreamer_pipeline_string)
            return
        # Grab the first frame to start the video capturing
        self.grabbed, self.frame = self.video_capture.read()

    def start(self):
        if self.running:
            print('Video capturing is already running')
            return None
        # create a thread to read the camera image
        if self.video_capture != None:
            self.running=True
            self.read_thread = threading.Thread(target=self.updateCamera)
            self.read_thread.start()
        return self

    def stop(self):
        self.running=False
        self.read_thread.join()

    def updateCamera(self):
        # This is the thread to read images from the camera
        while self.running:
            try:
                grabbed, frame = self.video_capture.read()
                with self.read_lock:
                    self.grabbed=grabbed
                    self.frame=frame
            except RuntimeError:
                print("Could not read image from camera")
        # FIX ME - stop and cleanup thread
        # Something bad happened
        

    def read(self):
        with self.read_lock:
            frame = self.frame.copy()
            grabbed=self.grabbed
        return grabbed, frame

    def release(self):
        if self.video_capture != None:
            self.video_capture.release()
            self.video_capture = None
        # Now kill the thread
        if self.read_thread != None:
            self.read_thread.join()


# Currently there are setting frame rate on CSI Camera on Nano through gstreamer
# Here we directly select sensor_mode 3 (1280x720, 59.9999 fps)
def gstreamer_pipeline(
    sensor_id=0,
    sensor_mode=3,
    capture_width=1280,
    capture_height=720,
    display_width=1280,
    display_height=720,
    framerate=30,
    flip_method=0,
):
    return (
        "nvarguscamerasrc sensor-id=%d sensor-mode=%d ! "
        "video/x-raw(memory:NVMM), "
        "width=(int)%d, height=(int)%d, "
        "format=(string)NV12, framerate=(fraction)%d/1 ! "
        "nvvidconv flip-method=%d ! "
        "video/x-raw, width=(int)%d, height=(int)%d, format=(string)BGRx ! "
        "videoconvert ! "
        "video/x-raw, format=(string)BGR ! appsink"
        % (
            sensor_id,
            sensor_mode,
            capture_width,
            capture_height,
            framerate,
            flip_method,
            display_width,
            display_height,
        )
    )


def start_cameras():
    left_camera = CSI_Camera()
    left_camera.open(
        gstreamer_pipeline(
            sensor_id=0,
            sensor_mode=3,
            flip_method=0,
            display_height=540,
            display_width=960,
        )
    )
    left_camera.start()

    right_camera = CSI_Camera()
    right_camera.open(
        gstreamer_pipeline(
            sensor_id=1,
            sensor_mode=3,
            flip_method=0,
            display_height=540,
            display_width=960,
        )
    )
    right_camera.start()

    cv2.namedWindow("CSI-AV Cameras", cv2.WINDOW_AUTOSIZE)

    if (
        not left_camera.video_capture.isOpened()
        or not right_camera.video_capture.isOpened()
    ):
        # Cameras did not open, or no camera attached

        print("Unable to open any cameras")
        # TODO: Proper Cleanup
        SystemExit(0)

    counter = 0
    t2 = datetime.now()
#Main stuff here
    while True:
        
        _ , left_image=left_camera.read()
        _ , right_image=right_camera.read()
        camera_images = np.hstack((left_image, right_image))
        cv2.imshow("CSI Cameras", camera_images)
        


        t1 = datetime.now()
        cntdwn_timer = countdown - int ((t1-t2).total_seconds())
        # If cowntdown is zero - let's record next image
        if cntdwn_timer == -1:
            counter += 1

            filename = './scenes/scene_'+ str(counter) + 'x'+'_'+ '.png'
            #img = cv2.imread(camera_images)
            #cv2.imwrite(os.path.join(os.path.expanduser('~'),'CSI-Camera', filename), camera_images)
            cv2.imwrite('/home/aryan/CSI-Camera/{}'.format(filename), camera_images)
            print (' monkey'+filename)
            t2 = datetime.now()
            time.sleep(1)
            cntdwn_timer = 0      # To avoid "-1" timer display 
            next
        

        # This also acts as
        keyCode = cv2.waitKey(30) & 0xFF
        # Stop the program on the ESC key
        if keyCode == 27:
            break

    left_camera.stop()
    left_camera.release()
    right_camera.stop()
    right_camera.release()
    cv2.destroyAllWindows()


if __name__ == "__main__":
    start_cameras()

Answer 1

Put breakpoint on line where you want to save image. Inspect image you want to save:

1. Does it have data inside?
2. Does it have camera_images.shape ?
3. What is return value of cv2.imwrite function?
4. Does path you are trying to write really exist?
5. Did you appended .png or .jpg ?