add_watermark.py

from PIL import Image

def watermark(img_path, watermark_path, output_path):
    # watermark_path is the image of watermark. Not text
    with Image.open(img_path) as im:
        width, height = int(im.size[0]), int(im.size[1])
        x_interval = int(width / 10)
        y_interval = int(height / 10)
        with Image.open(watermark_path) as watermark:
            # Load watermark and resize to fit
            watermark = watermark.resize((x_interval, y_interval))
            # Composite into image
            for i in range(0, width, x_interval):
                for j in range(0, height, y_interval):
                    im.paste(watermark, (i, j), watermark)
            im.save(output_path)
    return output_path