main.py

from PIL import Image, ImageOps
import math

def convolve(img, sz, step):
    # If the pixels are an odd size, a whole number is needed.
    start = math.floor(sz / 2)
    con_pixels = []
    for x in range(start, img.size[0] - 1, step):
        for y in range(start, img.size[1] - 1, step):

            # top row
            tl = img.getpixel((y-1, x-1))
            tc = img.getpixel((y - 1, x))
            tr = img.getpixel((y - 1, x + 1))

            # center row
            lc = img.getpixel((y - 1, x - 1))
            cc = img.getpixel((y - 1, x))
            rc = img.getpixel((y - 1, x + 1))

            # bottom row
            bl = img.getpixel((y + 1, x - 1))
            bc = img.getpixel((y + 1, x))
            br = img.getpixel((y + 1, x + 1))
            
            
            # left row
            ll = img.getpixel((y + 1, x - 1))
            lc = img.getpixel((y + 1, x))
            lr = img.getpixel((y + 1, x + 1))
            
            
            # right row
            rl = img.getpixel((y - 1, x - 1))
            rc = img.getpixel((y - 1, x))
            rr = img.getpixel((y - 1, x + 1))

            sum = tl*3 + tc*10 + tr*3 + lc*0 + cc*0 + rc*0 + bl*-3 + bc*-10 + br*-3 + ll*-3 +lc*-10+ lr*-3 +rl*3 +rc*10 + rr *3
            div = 1
            y_ave = math.floor(sum / div)            
            # print("y_ave ",y_ave)

            sum = tl*3 + tc * 0 + tr * -3 + lc * 10 + cc * 0 + rc * -10 + bl * 3 + bc * 0 + br * -3 + ll*-3 +lc*-10+ lr*-3 +rl*3 +rc*10 + rr *3
            div = 1
            x_ave = math.floor(sum / div)
            
            
            sum = tl*3 + tc*10 + tr*3 + lc*0 + cc*0 + rc*0 + bl*-3 + bc*-10 + br*-3 + ll*-3 +lc*-10+ lr*-3 +rl*3 +rc*10 + rr *3
            div = 1
            z_ave = math.floor(sum / div)            
            # print("y_ave ",y_ave)

            sum = tl*3 + tc * 0 + tr * -3 + lc * 10 + cc * 0 + rc * -10 + bl * 3 + bc * 0 + br * -3 + ll*-3 +lc*-10+ lr*-3 +rl*3 +rc*10 + rr *3
            div = 1
            u_ave = math.floor(sum / div)
            
            ave = math.floor(x_ave + y_ave + z_ave + u_ave)
            if ave == 0:
                con_pixels.append(ave)
            elif ave == 1:
                con_pixels.append(ave)
            elif ave <= 9690:
                con_pixels.append(ave)               
            else:
                con_pixels.append(ave)
    # print(con_pixels)
            

    # New image is smaller than original and needs to be a whole number
    dims = (math.floor(img.size[0]/step) - 1, math.floor(img.size[1]/step) - 1)
    output = Image.new("L", dims)
    print(len(con_pixels))
    output.putdata(con_pixels)
    output.show()
# end def convolve(img, sz)

def main():
    og_image = Image.open("demo.png")
    # convert to grayscale
    gray_image = ImageOps.grayscale(og_image)
    # open original for comparison
    gray_image.show()
    # kernel size of 3x3
    convolve(gray_image, 3, 2)
# end def main():

if __name__ == "__main__":
    main()