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() 

Answer 2

Expanding on the great answer by fraxel, I wrote a program which takes in a folder of (.png) images, a number of pixels for the width of the collage, and the number of pictures per row, and does all the calculations for you.

#Evan Russenberger-Rosica #Create a Grid/Matrix of Images import PIL, os, glob from PIL import Image from math import ceil, floor  PATH = r"C:\Users\path\to\images"  frame_width = 1920 images_per_row = 5 padding = 2  os.chdir(PATH)  images = glob.glob("*.png") images = images[:30]                #get the first 30 images  img_width, img_height = Image.open(images[0]).size sf = (frame_width-(images_per_row-1)*padding)/(images_per_row*img_width)       #scaling factor scaled_img_width = ceil(img_width*sf)                   #s scaled_img_height = ceil(img_height*sf)  number_of_rows = ceil(len(images)/images_per_row) frame_height = ceil(sf*img_height*number_of_rows)   new_im = Image.new('RGB', (frame_width, frame_height))  i,j=0,0 for num, im in enumerate(images):     if num%images_per_row==0:         i=0     im = Image.open(im)     #Here I resize my opened image, so it is no bigger than 100,100     im.thumbnail((scaled_img_width,scaled_img_height))     #Iterate through a 4 by 4 grid with 100 spacing, to place my image     y_cord = (j//images_per_row)*scaled_img_height     new_im.paste(im, (i,y_cord))     print(i, y_cord)     i=(i+scaled_img_width)+padding     j+=1  new_im.show() new_im.save("out.jpg", "JPEG", quality=80, optimize=True, progressive=True)