02-Dense Optical Flow.ipynb

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    "# import libraries\n",
    "import cv2\n",
    "import numpy as np\n",
    "\n",
    "# video capture\n",
    "cap = cv2.VideoCapture('Video/chaplin.mp4')\n",
    "\n",
    "# read the capture and get the first frame\n",
    "ret, first_frame = cap.read()\n",
    "\n",
    "# convert frame to grayscale\n",
    "prev_gray = cv2.cvtColor(first_frame, cv2.COLOR_BGR2GRAY)\n",
    "\n",
    "# create an image with the same dimensions as the frame for later drawing purposes\n",
    "mask = np.zeros(first_frame)\n",
    "\n",
    "# saturation to maximum\n",
    "mask[..., 1] = 255\n",
    "\n",
    "#while loop\n",
    "while (cap.isOpened()):\n",
    "    \n",
    "    # read the capture and get the first frame\n",
    "    ret, frame = cap.read()\n",
    "    \n",
    "    # open new window and display the input frame\n",
    "    cv2.imshow('input', frame)\n",
    "    \n",
    "    # convert all frame to grayscale (previously we did only for the first frame)\n",
    "    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)\n",
    "    \n",
    "    # calculate dense optical flow by Farneback\n",
    "    flow = cv2.calcOpticalFlowFarneback(prev_gray, gray, None, 0.5, 3, 15, 1.2, 0)\n",
    "    \n",
    "    # compute magnitude and angle\n",
    "    magn, angle = cv2.cartToPolar(flow[..., 0], flow[..., 1])\n",
    "    \n",
    "    # set image hue depending on the optical flow direction\n",
    "    mask[..., 0] = angle*180/np.pi/2\n",
    "    \n",
    "    # normalize the magnitude\n",
    "    mask[..., 2] = cv2.normalize(magn, None, 0, 255, cv2.NORM_MINIMAX)\n",
    "    \n",
    "    # convert HSV to RGB\n",
    "    rgb = cv2.cvtColor(mask, cv2.COLOR_HSV2RGB)\n",
    "    \n",
    "    # open new window and display the output\n",
    "    cv2.imshow(\"Dense Optical Flow\", rgb)\n",
    "    \n",
    "    # update previous frame\n",
    "    prev_gray = gray\n",
    "    \n",
    "    # close the frame\n",
    "    if cv2.waitKey(30) & 0xFF ==ord(\"q\"):\n",
    "        break\n",
    "\n",
    "\n",
    "# release and destroy\n",
    "cap.release()\n",
    "cv2.destroyAllWindows()\n"
   ]
  }
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