python - 加载 TrueType 字体到 OpenCV

Question

我们可以加载自定义 TrueType 字体并将其与 cv2.putText 函数一起使用吗？

font = cv2.FONT_HERSHEY_SIMPLEX
cv2.putText(img,'OpenCV',(10,500), font, 4,(255,255,255),2,cv2.LINE_AA)

Answer 1

在 OpenCV 中，仅支持 Hershey 字体的一个子集。

在 opencv2/core.hpp 中，您可以找到这个枚举 HersheyFonts。

//! Only a subset of Hershey fonts
enum HersheyFonts {
    FONT_HERSHEY_SIMPLEX        = 0, //!< normal size sans-serif font
    FONT_HERSHEY_PLAIN          = 1, //!< small size sans-serif font
    FONT_HERSHEY_DUPLEX         = 2, //!< normal size sans-serif font (more complex than FONT_HERSHEY_SIMPLEX)
    FONT_HERSHEY_COMPLEX        = 3, //!< normal size serif font
    FONT_HERSHEY_TRIPLEX        = 4, //!< normal size serif font (more complex than FONT_HERSHEY_COMPLEX)
    FONT_HERSHEY_COMPLEX_SMALL  = 5, //!< smaller version of FONT_HERSHEY_COMPLEX
    FONT_HERSHEY_SCRIPT_SIMPLEX = 6, //!< hand-writing style font
    FONT_HERSHEY_SCRIPT_COMPLEX = 7, //!< more complex variant of FONT_HERSHEY_SCRIPT_SIMPLEX
    FONT_ITALIC                 = 16 //!< flag for italic font
};

如果你想使用自定义字体，你可以试试 PIL.ImageFont。

这里给出了一个基本的例子:

import numpy as np
from PIL import ImageFont, ImageDraw, Image
import cv2
import time

## Make canvas and set the color
img = np.zeros((200,400,3),np.uint8)
b,g,r,a = 0,255,0,0

## Use cv2.FONT_HERSHEY_XXX to write English.
text = time.strftime("%Y/%m/%d %H:%M:%S %Z", time.localtime()) 
cv2.putText(img,  text, (50,50), cv2.FONT_HERSHEY_SIMPLEX, 0.7, (b,g,r), 1, cv2.LINE_AA)

## Use simsum.ttc to write Chinese.
fontpath = "./simsun.ttc"     
font = ImageFont.truetype(fontpath, 32)
img_pil = Image.fromarray(img)
draw = ImageDraw.Draw(img_pil)
draw.text((50, 100),  "国庆节/中秋节 快乐!", font = font, fill = (b, g, r, a))
img = np.array(img_pil)

## Display 
cv2.imshow("res", img);cv2.waitKey();cv2.destroyAllWindows()
cv2.imwrite("res.png", img)