Averaging filter (high pass).ipynb

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    "# High Pass SPatial Domain Filtering \n",
    "\n",
    "\n",
    "'''\n",
    "High Pass Filtering: It eliminates low-frequency regions \n",
    "while retaining or enhancing the high-frequency components. \n",
    "A high pass filtering mask is as shown.\n",
    "\n",
    "-1/9 -1/9 -1/9\n",
    "-1/9 8/9 -1/9\n",
    "-1/9 -1/9 -1/9\n",
    "\n",
    "'''\n",
    "\n",
    "import cv2\n",
    "import matplotlib.pyplot as plt \n",
    "import math\n",
    "import numpy as np\n",
    "\n",
    "\t\n",
    "# Read the image \n",
    "img = cv2.imread('images/board.png', 0) \n",
    "\n",
    "# Obtain number of rows and columns \n",
    "# of the image \n",
    "m, n = img.shape \n",
    "\n",
    "# Develop Averaging filter(3, 3) mask \n",
    "mask = np.ones([3, 3], dtype = int) \n",
    "mask = mask / -9\n",
    "\n",
    "# Convolve the 3X3 mask over the image \n",
    "img_new = np.zeros([m, n]) \n",
    "\n",
    "for i in range(1, m-1): \n",
    "\tfor j in range(1, n-1): \n",
    "\t\ttemp = img[i-1, j-1]*mask[0, 0]+img[i-1, j]*mask[0, 1]+img[i-1, j + 1]*mask[0, 2]+img[i, j-1]*mask[1, 0]+ img[i, j]*mask[1, 1]+img[i, j + 1]*mask[1, 2]+img[i + 1, j-1]*mask[2, 0]+img[i + 1, j]*mask[2, 1]+img[i + 1, j + 1]*mask[2, 2] \n",
    "\t\t\n",
    "\t\timg_new[i, j]= temp \n",
    "\t\t\n",
    "img_new = img_new.astype(np.uint8) \n",
    "\n",
    "\n",
    "# Display the images\n",
    "plt.imshow(img) \n",
    "plt.show()\n",
    "\n",
    "# Display the images\n",
    "plt.imshow(img_new) \n",
    "plt.show()"
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