[Python] Average color over kernel-sized position on image

from PIL import Image

# PIL accesses images in Cartesian co-ordinates, so it is Image[columns, rows]
# img = Image.new( 'RGB', (1280, 720), "black") # create a new black image
#img = Image.open("rsz_2lemibrat.jpg")
img = Image.open("lena.jpg")
pixels = img.load() # create the pixel map

# https://stackoverflow.com/questions/6667201/how-to-define-a-two-dimensional-array-in-python
# Creates a list containing 32 lists, each of 32 items, all set to 0
k_w, k_h = 40, 40
x_pos, y_pos = 200, 250
k_i, k_j = 0, 0

kernel = {}
# kernel = [[0 for x in range(w)] for y in range(h)]

print(img.size)     # Prints (250, 250)

#for i in range(img.size[0]):    # for every col:
    #for j in range(img.size[1]):    # For every row
        #pixels[i,j] = (i, j, 100) # set the colour accordingly
        # print(pixels[i,j][0])

for i in range(x_pos, x_pos + k_w):
    for j in range (y_pos, y_pos + k_h):
        kernel[k_i, k_j] = pixels[i, j]

        k_j += 1
        print('k_j = ' + str(k_j) + ' a vrednost RGB = ' + str(pixels[i, j]))
        if k_j == k_h:
            k_j = 0

    k_i += 1
    print('k_i = ' + str(k_i) + ' a vrednost RGB = ' + str(pixels[i, j]))
    if k_i == k_w:
        k_i = 0


#print('Trenutno ispisujem: ' + str(kernel[22,23]))
k_R, k_G, k_B = 0, 0, 0
for i in range(0, k_w):
    for j in range (0, k_h):
        k_R += kernel[i, j][0]
        k_G += kernel[i, j][1]
        k_B += kernel[i, j][2]
        #print(kernel[i, j])

# Hehe, nisi dovoljno mocan ako ne mozes ovo ha ha ha
# k_R, k_G, k_B /= 32, 32, 32
k_R /= k_w * k_h
k_G /= k_w * k_h
k_B /= k_w * k_h
print('Srednja vrijednost: R = ' + str(k_R) + ' G = ' + str(k_G) + ' B = ' + str(k_B))


for i in range(x_pos, x_pos + k_w):
    for j in range (y_pos, y_pos + k_h):
        pixels[i, j] = (k_R, k_G, k_B)

img.show()