Fit multiple 35mm x 45mm passport photos into a 4x6-sized printable format

passport_photo_4x6.py

import argparse
import math

from PIL import Image, ImageDraw


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('-o', dest='output_file', required=True, help='output file')
    parser.add_argument('input_files', metavar='FILE', nargs='+')
    args = parser.parse_args()

    def snap(x):
        return int(math.ceil(x))

    # Load input files and resize all images
    img = [Image.open(fname) for fname in args.input_files]
    for i in range(1, len(img)):
        img[i] = img[i].resize(img[0].size)

    # Allocate slots 
    if len(img) in (1, 2, 4, 8):
        rep = int(8 / len(img))
        slot = []
        for obj in img:
            slot.extend([obj] * rep)
    else:
        print('Can only process 1, 2, or 4 input files')
        return

    # Assuming input is 35mm x 45mm, target (4x6) will be 101.6mm x 152.4mm in landscape
    print('Image size:', img[0].size)

    width, height = img[0].size
    ppmm = width / 35
    new_width, new_height = snap(height / 45 * 152.4), snap(width / 35 * 101.6)

    # New image in landscape
    new_img = Image.new('RGB', (new_width, new_height), color='white')
    print('Target size:', new_img.size)

    offset = snap(ppmm)
    margin_left = (new_width - 4 * (width + 2*offset)) / 2
    margin_top = (new_height - 2 * (height + 2*offset)) / 2

    new_draw = ImageDraw.Draw(new_img)
    for i in range(4):
        for j in range(2):
            x = snap(margin_left + offset + i * (width + 2*offset))
            y = snap(margin_top + offset + j * (height + 2*offset))
            new_img.paste(slot[i+4*j], (x, y))
            
            new_draw.line((x-offset, y-offset, x+width+offset, y-offset), fill='#333333')
            new_draw.line((x+width+offset, y-offset, x+width+offset, y+height+offset), fill='#333333')
            new_draw.line((x-offset, y+height+offset, x+width+offset, y+height+offset), fill='#333333')
            new_draw.line((x-offset, y-offset, x-offset, y+height+offset), fill='#333333')
            
    new_img.save(args.output_file)
    print(f'Output saved to {args.output_file}')


if __name__ == '__main__':
    main()