gistfile1.py

from PIL import Image, ImageDraw
from sys import argv
 
def gray_scale(img):
    pixel = img.load()
    w, h = img.size
    for i in range(w):
        for j in range(h):
            r, g, b = pixel[i,j]
            media = (r+g+b)/3
            pixel[i,j] = (media, media, media)
    return img

def lista_horizontal(img):
    pixel = img.load()
    w, h = img.size
    return lista_histograma(w, h, pixel, 'horizontal')

def lista_vertical(img):
    pixel = img.load()
    w, h = img.size
    return lista_histograma(h, w, pixel, 'vertical')

def lista_histograma(a, b, pixel, type_l):
    lista = list()
    for x in range(a):
        suma = 0
        for y in range(b):
            if(type_l == 'horizontal'): suma += int(pixel[x,y][0])
            else: suma += int(pixel[y,x][0])
        lista.append(suma)
    return lista

def lista_minimos(list_hist):
    lista = list()
    for i in range(len(list_hist)):
        try:
            if(list_hist[i-1] > list_hist[i] and list_hist[i+1] > list_hist[i]): lista.append(i)
        except:
            pass
    lista.sort()
    return lista

def dibujar_lineas(img, horizontal, vertical):
    w, h = img.size
    draw = ImageDraw.Draw(img)
    azul = (0, 255, 0)
    verde = (0, 0, 255)
    
    for x in horizontal:
        draw.line((x, 0, x, w), azul)
 
    for y in vertical:
        draw.line((0, y, h, y), verde)
 
    img.save("histograma.png", 'PNG')

def main():

    img = Image.open(argv[1])
    img = gray_scale(img)
    
    horizontal = list(lista_horizontal(img))
    vertical = lista_vertical(img)
    
    horizontal = lista_minimos(horizontal)
    vertical = lista_minimos(vertical)
    img = Image.open(argv[1])
    dibujar_lineas(img, horizontal, vertical)

main()