Outline filter

# -*- coding: utf-8 -*-
"""
Created on Mon Sep 12 15:46:58 2022
 
@author: elodees
"""
 
import cv2
import numpy as np
from matplotlib import pyplot as plt
from PIL import Image
 
img = cv2.imread("city.jpg")
 
plt.imshow(cv2.cvtColor(img, cv2.COLOR_BGR2RGB))
plt.axis('off')
plt.title('Originale image')
plt.show()
 
height, width, depth = np.shape(img)
 
new_im = Image.new('RGB', (width, height))
 
pixel_map = new_im.load()
 
# North Direction Edge
Kernel = [[-1, -1, -1],
          [-1,  8, -1],
          [-1, -1, -1]]
 
H = int(len(Kernel))
 
for j in range(0, width - H):
    for i in range(0, height - H):
 
        summ = 0
 
        for k in range(0, H):
            for l in range(0, H):
 
                # RGB to Gray
                img[i+k][j+l][0] = img[i+k][j+l][1] = img[i+k][j+l][2] = 0.2989 * img[i+k][j+l][0] + 0.5870 * img[i+k][j+l][1] + 0.1140 * img[i+k][j+l][2]
 
                summ = summ + Kernel[k][l] * img[i+k][j+l][0]
 
        if(summ > 255):
           summ = 255
 
        if(summ < 0):
           summ = 0
 
        pixel_map[j, i] = (summ, summ, summ)
 
plt.imshow(new_im)
plt.axis('off')
plt.show()