Question

For example, a 3 pixel by 3 pixel jpeg image of a checkerboard should be something like

[[#000000, #FFFFFF, #000000],
[#FFFFFF, #000000, #FFFFFF],
[#000000, #FFFFFF, #000000]]

I feel like I may need to download PIL, but I cannot tell what the module does from their website. I also need to be able to generate images from these types of arrays. Thank you!

Answer 1

Use the Image.getdata method. The method returns a generator that you can iterate over:

from PIL import Image
img = Image.open("a.png")
data = img.getdata()
for (r, g, b, a) in data:
    # do something with the pixel values

To go the other way you use Image.putdata. This generates a tiny checkerboard picture:

>>> img = Image.new("L", (3, 3))
>>> data = [0, 255, 0, 255, 0, 255, 0, 255, 0]
>>> img.putdata(data)
>>> img.save("checkerboard.png")

Here I created a grayscale image (only one “luminescence” channel) and so I just used a single integer value for each pixel.