make_overlay.py

def make_overlay(imagename, box, outname):
    '''creates a PNG image of base with overlayed colored boxes. Useful for human review'''
    if 'size' not in box:
        return

    img = Image.open(imagename).convert('RGB')
    draw = ImageDraw.Draw(img, 'RGBA')

    for key,color in [
        ('title', (255, 0, 0, 128)),
        ('authors', (0, 255, 0, 128)),
        ('abstract', (0, 0, 255, 128))
    ]:
        bbox = box.get(key)
        if bbox:
            draw.rectangle(bbox, fill=color)

    del draw
    img.save(outname, 'PNG')