python - Pythonでテキストを描画する

Question

数値のテキスト描画を追加しようとして、次のコード (この回答から派生) があります。うまくいきません。イメージを作成せず、cmd プロンプトが速すぎて、スローされているエラーを確認できません。

#!/usr/bin/env python
import os.path
import sys
from time import strftime
import Image
import ImageDraw
import ImageFont

row_size = 3
margin = 3

def generate_montage(filenames, output_fn):
    images = [Image.open(filename) for filename in filenames]

    width = max(image.size[0] + margin for image in images)*row_size
    height = sum(image.size[1] + margin for image in images)

    montage = Image.new(mode='RGBA', size=(width, height), color=(0,0,0,255))

    image_font = ImageFont.truetype('font/Helvetica.ttf', 18)
    draw = ImageDraw.Draw(montage)

    max_x = 0
    max_y = 0
    offset_x = 0
    offset_y = 0
    for i,image in enumerate(images):
        montage.paste(image, (offset_x, offset_y))

        text_coords = offset_x + image.size[0] - 45, offset_y + 120
        draw.text(text_coords, '#{0}'.format(i+1), font=image_font)

        max_x = max(max_x, offset_x + image.size[0])
        max_y = max(max_y, offset_y + image.size[1])

        if i % row_size == row_size-1:
            offset_y = max_y + margin
            offset_x = 0
        else:
            offset_x += margin + image.size[0]

    montage = montage.crop((0, 0, max_x, max_y))
    montage.save(output_fn)

if __name__ == '__main__':
    basename = strftime("Montage %Y-%m-%d at %H.%M.%S.png")
    exedir = os.path.dirname(os.path.abspath(sys.argv[0]))
    filename = os.path.join(exedir, basename)
    generate_montage(sys.argv[1:], filename)