from PIL import Image
im1=Image.open("rouge1.jpg")
L,H=im1.size
im2 = Image.new ("RGB",(L,H))
S=int(input("Entrer un seuil de nuance de rouge: "))
for y in range(H):
    for x in range(L):
        p = im1.getpixel((x,y))
        LUM=0,21*p[0]+0,71*p[1]+0,7*p[2]
        if p[0]>p[1] and p[0]>p[2] and p[0]<S:
         im2.putpixel((x,y), (LUM,LUM,LUM))
        else:
            im2.putpixel((x,y), (p[0],p[1],p[2]))
im2.save("image-seuillee.pgm")
im2.show()