How do you merge images into a canvas using PIL/Pillow?

Question

I'm not familiar with PIL, but I know it's very easy to put a bunch of images into a grid in ImageMagick.

How do I, for example, put 16 images into a 4×4 grid where I can specify the gap between rows and columns?

Answer 1

This is easy to do in PIL too. Create an empty image and just paste in the images you want at whatever positions you need using paste. Here's a quick example:

import Image

#opens an image:
im = Image.open("1_tree.jpg")
#creates a new empty image, RGB mode, and size 400 by 400.
new_im = Image.new('RGB', (400,400))

#Here I resize my opened image, so it is no bigger than 100,100
im.thumbnail((100,100))
#Iterate through a 4 by 4 grid with 100 spacing, to place my image
for i in xrange(0,500,100):
    for j in xrange(0,500,100):
        #I change brightness of the images, just to emphasise they are unique copies.
        im=Image.eval(im,lambda x: x+(i+j)/30)
        #paste the image at location i,j:
        new_im.paste(im, (i,j))

new_im.show()