im_hstack.py

from PIL import Image

def im_hstack(images):
    min_height = min([im.height for im in images])
    for im in images:
        if im.height != min_height:
            im.thumbnail((im.width, min_height))
    total_width = sum([im.width for im in images])
    panorama = Image.new('RGB', (total_width, min_height))
    x_offset = 0
    for im in images:
        panorama.paste(im, (x_offset,0))
        x_offset += im.width
    return panorama