利用 PIL 的图片处理库添加水印的实现.

#!/usr/bin/python2
# -*- coding: utf-8 -*-
import os
from PIL import Image, ImageDraw, ImageFont

def add_watermark_fun1(img_pil, text):
    print("[INFO]PIL image info: ", img_pil.size)
    img_rgba = img_pil.convert("RGBA")

    text_img = Image.new("RGBA", img_rgba.size, (255, 255, 255, 0))
    draw = ImageDraw.Draw(text_img)

    font = ImageFont.truetype('NotoSansCJK-Black.ttc', 30)  # 字体及字体大小
    print("[INFO]Text info: ", draw.textsize(text, font=font))

    text_position = (20, 20)
    # 文本位置, 颜色, 透明度
    draw.text(text_position, text, font=font, fill=(128, 0, 0, 50))

    # 合成水印图片
    img_with_watermark = Image.alpha_composite(img_rgba, text_img)
    
    # 显示加水印后的图片
    img_with_watermark.show()

    return img_with_watermark.convert("RGB")


def add_watermark_fun2(img_pil, text):
    print("[INFO]PIL image info: ", img_pil.size)
    width, height = img_pil.width, img_pil.height

    #
    new_img = Image.new('RGBA', (width * 3, height * 3), (0, 0, 0, 0))
    new_img.paste(img_pil, (width, height))
    img_rgba = new_img.convert('RGBA')

    #
    text_img = Image.new('RGBA', img_rgba.size, (255, 255, 255, 0))
    draw = ImageDraw.Draw(text_img)

    # 添加水印
    # 文本位置, 颜色, 透明度
    font = ImageFont.truetype('NotoSansCJK-Black.ttc', 20)
    for i in range(0, img_rgba.size[0], len(text) * 20 + 80):
        for j in range(0, img_rgba.size[1], 200):
            draw.text((i, j), text, font=font, fill=(0, 0, 0, 50))

    # 旋转文字 45 度
    text_img = text_img.rotate(-45)

    # 合成水印图片
    img_with_watermark = Image.alpha_composite(img_rgba, text_img)

    # 原始图片尺寸
    img_with_watermark = img_with_watermark.crop((width, height, width * 2, height * 2))

    img_with_watermark.show()
    
    return img_with_watermark.convert("RGB")

if __name__ == '__main__':
    img_file = "/path/to/test.jpg"
    text = u'AIUAI 测试使用'
    img_pil = Image.open(img_file)
    
    #out_img = add_watermark_fun1(img_pil, text)
    out_img = add_watermark_fun2(img_pil, text)

    out_img.save("/path/to/save/out_img.jpg", 'JPEG', quality=100)

    print("[INFO]Done.")

如：