Create a poster based on a video. This can be useful for educational videos for your children.

create_poster.py

# # Recipe for creating a poster based on a video
#
# 1. download a video (for example, youtube-dl)
# 2. extract images from the video, say every second one frame (ffmpeg)
# 3. choose the images you want and delete the images you don't want
# 4. (this notebook) align the images horizontally and vertically based on the numbering


# got this part from https://note.nkmk.me/en/python-pillow-concat-images/
from PIL import Image

def get_concat_h(im1, im2):
    dst = Image.new('RGB', (im1.width + im2.width, im1.height))
    dst.paste(im1, (0, 0))
    dst.paste(im2, (im1.width, 0))
    return dst

def get_concat_v(im1, im2):
    dst = Image.new('RGB', (im1.width, im1.height + im2.height))
    dst.paste(im1, (0, 0))
    dst.paste(im2, (0, im1.height))
    return dst


import os

# get all the image files in a directory:
imagepath = '/Users/ben/Dropbox/nico/animals/'
images = [image for image in os.listdir(imagepath) if image.endswith('jpeg')]


import re

def get_number(filename):
    """This is for ordering the images. Each image should
    have a number in the filename.
    """
    return int(re.search(r'[0-9][0-9]*', filename).group())

images = sorted(images, key=lambda item: get_number(item))


# ncols is the one parameter you need to set. This is the number of columns in the poster.
# ncols - The number of images in one row
ncols = 4
rows = []
row = []
for image in images:
    row.append(Image.open(os.path.join(imagepath, image)))
    if len(row) >= ncols:
        rows.append(row)
        row = []
if len(row) > 0:
    nblanks = ncols - len(row)
    for bl in range(nblanks):
        # The background is set to white:
        row.append(Image.new('RGB', row[0].size, (255, 255, 255)))
    rows.append(row)

if len(rows) % 2 == 1:
    row = []
    for bl in range(ncols):
        row.append(Image.new('RGB', rows[0][0].size, (255, 255, 255)))
    rows.append(row)


def grouped(iterable, n=2):
    """return iterator over n objects
    """
    return zip(*[iter(iterable)]*n)

def concat_images(horiz_images, op=get_concat_h):
    """this concatenates horizonally or vertically
    (depending on the operation specified by the op parameter)
    """
    while len(horiz_images) > 1:
        new_image = []
        for image1, image2 in grouped(horiz_images, 2):
            new_image.append(op(image1, image2))
        horiz_images = new_image
    return horiz_images


# first: horizontally concatenating in order to get the rows
image_rows = []
for row in rows:
    image_rows.append(concat_images(row)[0])


# second: vertically concatenating the rows in order to get the whole poster
image = concat_images(image_rows, op=get_concat_v)[0]


# save the image:
image.save(
    os.path.join(imagepath, 'animal_poster.png'),
    dpi=(350, 350)
)