[python] 'tuple' object does not support item assignment

I am using the PIL library.

I am trying to make an image look red-er, this is what i've got.

from PIL import Image
image = Image.open('balloon.jpg')
pixels = list(image.getdata())
for pixel in pixels: 
    pixel[0] = pixel[0] + 20    
image.putdata(pixels)
image.save('new.bmp')

However I get this error: TypeError: 'tuple' object does not support item assignment

A tuple is immutable and thus you get the error you posted.

>>> pixels = [1, 2, 3]
>>> pixels[0] = 5
>>> pixels = (1, 2, 3)
>>> pixels[0] = 5
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment

In your specific case, as correctly pointed out in other answers, you should write:

pixel = (pixel[0] + 20, pixel[1], pixel[2])

You probably want the next transformation for you pixels:

pixels = map(list, image.getdata())

Tuples, in python can't have their values changed. If you'd like to change the contained values though I suggest using a list:

[1,2,3] not (1,2,3)

You have misspelt the second pixels as pixel. The following works:

pixels = [1,2,3]
pixels[0] = 5

It appears that due to the typo you were trying to accidentally modify some tuple called pixel, and in Python tuples are immutable. Hence the confusing error message.

The second line should have been pixels[0], with an S. You probably have a tuple named pixel, and tuples are immutable. Construct new pixels instead:

image = Image.open('balloon.jpg')

pixels = [(pix[0] + 20,) + pix[1:] for pix in image.getdata()]

image.putdate(pixels)