Pink tint on pixel conversion using PIL Image

Question

I am trying to change half of the pixels in an image and there is always a pink tint to them. Even in an example of the code where the pixel RGB value remains the same, the image comes out tinted pink. Here is the code and the before and after image. What is causing the pink tint and how can I fix it?

from PIL import Image
im = Image.open('me.jpg')
pix = im.load()
q, w = (im.size)
s=0
a=0
x=0
y=0
while s<w:
    while a<(q/2):
        r, g, b = im.getpixel((x,y))
        pix[0+x,0+y] = (r,b,g)
        a=a+1
        x=x+1
    a=0
    x=0
    y=y+1
    s=s+1

im.save('me2.jpg')

Example

Answer 1

You've reversed the order of g and b when assigning the colours you extracted:

pix[0+x,0+y] = (r,b,g)

If you put them back in rgb order, it works:

pix[0+x,0+y] = (r,g,b)