from PIL import Image, ImageFont, ImageDraw, ImageEnhance, ImageChops
import cv2
import math
import numpy as np


def crop_image(im):
    """裁剪图片边缘空白"""
    bg = Image.new(mode="RGBA", size=im.size)
    bbox = ImageChops.difference(im, bg).getbbox()
    if bbox:
        return im.crop(bbox)
    return im


def set_opacity(im, opacity):
    """设置水印透明度"""
    assert 0 <= opacity <= 1
    alpha = im.split()[3]
    alpha = ImageEnhance.Brightness(alpha).enhance(opacity)
    im.putalpha(alpha)
    return im


def get_mark_img(text, color="#8B8B1B", size=30, opacity=0.15):
    """生成水印图片"""
    width = len(text) * size
    mark = Image.new(mode="RGBA", size=(width, size + 20))
    draw_table = ImageDraw.Draw(im=mark)
    draw_table.text(
        xy=(0, 0),
        text=text,
        fill=color,
        font=ImageFont.truetype("./bird.ttf", size=size),
    )
    del draw_table
    mark = crop_image(mark)  # 裁剪空白
    set_opacity(mark, opacity)  # 透明度
    return mark


# 读取OpenCV图像
img = cv2.imread("test.jpg")
# OpenCV转PIL格式
im = Image.fromarray(cv2.cvtColor(img, cv2.COLOR_BGR2RGB))
# 生成水印图标
mark = get_mark_img("我是水印", "#FFFFFF", 30, 0.5)
# 将水印图标扩展并旋转生成水印大图
w, h = im.size
c = int(math.sqrt(w**2 + h**2))
mark2 = Image.new(mode="RGBA", size=(c, c))
y, idx = 0, 0
mark_w, mark_h = mark.size
space = 100  # 水印文字间隔
angle = 45  # 水印文字角度
while y < c:
    x = -int((mark_w + space) * 0.5 * idx)
    idx = (idx + 1) % 2
    while x < c:
        mark2.paste(mark, (x, y))
        x = x + mark_w + space
    y = y + mark_h + space
# 将水印大图旋转一定角度
mark2 = mark2.rotate(angle)
# 在原图上添加水印大图
if im.mode != "RGBA":
    im = im.convert("RGBA")
im.paste(mark2, (int((w - c) / 2), int((h - c) / 2)), mask=mark2.split()[3])
# PIL转OpenCV
img = cv2.cvtColor(np.asarray(im), cv2.COLOR_RGB2BGR)
# 保存图像
cv2.imwrite("result.jpg", img)

实现效果如下：


完整代码链接