92 lines
2.3 KiB
Python
92 lines
2.3 KiB
Python
# This script shows how to do simple processing on frames comming from a camera in OpenCV.
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# Kim S. Pedersen, 2015
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import cv2 # Import the OpenCV library
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import numpy as np # We also need numpy
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from pkg_resources import parse_version
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OPCV3 = parse_version(cv2.__version__) >= parse_version('3')
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def capPropId(prop):
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"""returns OpenCV VideoCapture property id given, e.g., "FPS
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This is needed because of differences in the Python interface in OpenCV 2.4 and 3.0
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"""
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return getattr(cv2 if OPCV3 else cv2.cv, ("" if OPCV3 else "CV_") + "CAP_PROP_" + prop)
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def gstreamer_pipeline(capture_width=1024, capture_height=720, framerate=30):
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"""Utility function for setting parameters for the gstreamer camera pipeline"""
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return (
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"libcamerasrc !"
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"video/x-raw, width=(int)%d, height=(int)%d, framerate=(fraction)%d/1 ! "
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"videoconvert ! "
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"appsink"
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% (
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capture_width,
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capture_height,
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framerate,
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)
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)
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print("OpenCV version = " + cv2.__version__)
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# Define some constants
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lowThreshold = 35
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ratio = 3
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kernel_size = 3
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# Open a camera device for capturing
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cam = cv2.VideoCapture(gstreamer_pipeline(), apiPreference=cv2.CAP_GSTREAMER)
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if not cam.isOpened(): # Error
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print("Could not open camera")
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exit(-1)
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# Get camera properties
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width = int(cam.get(capPropId("FRAME_WIDTH")))
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height = int(cam.get(capPropId("FRAME_HEIGHT")))
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print("width = " + str(width) + ", Height = " + str(height))
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# Open a window
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WIN_RF = "Example 2"
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cv2.namedWindow(WIN_RF)
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cv2.moveWindow(WIN_RF, 100, 100)
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# Preallocate memory
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#gray_frame = np.zeros((height, width), dtype=np.uint8)
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while cv2.waitKey(4) == -1: # Wait for a key pressed event
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retval, frameReference = cam.read() # Read frame
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if not retval: # Error
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print(" < < < Game over! > > > ")
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exit(-1)
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# Convert the image to grayscale
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gray_frame = cv2.cvtColor( frameReference, cv2.COLOR_BGR2GRAY )
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# Reduce noise with a kernel 3x3
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edge_frame = cv2.blur( gray_frame, (3,3) )
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# Canny detector
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cv2.Canny( edge_frame, lowThreshold, lowThreshold*ratio, edge_frame, kernel_size )
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# Show frames
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cv2.imshow(WIN_RF, edge_frame)
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# Close all windows
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cv2.destroyAllWindows()
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# Finished successfully
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