Image Captcha¶

Unleash captivating security with image CAPTCHA mastery.

This module is compatibile with Pillow 9.4.0+.

Usage¶

Generating image CAPTCHA with the ImageCaptcha class is incredibly straightforward.

from io import BytesIO
from captcha.image import ImageCaptcha

captcha = ImageCaptcha()
data: BytesIO = captcha.generate('ABCD')

The result image would be something like:

../_images/image-demo.png — This image CAPTCHA is generated by above code¶

Fonts¶

The ImageCaptcha library comes with one built-in font named “DroidSansMono”, which is licensed under the Apache License 2.0. However, it is recommended to use your own custom fonts for generating CAPTCHA images.

custom_fonts = ['path/to/your/custom_font.ttf']
captcha = ImageCaptcha(fonts=[custom_fonts])

On the fly¶

Let’s explore how to use the CAPTCHA library to dynamically render image CAPTCHAs within a Flask application. This allows you to generate CAPTCHA images dynamically and serve them directly to users when they access a specific endpoint.

from flask import Flask, Response
from captcha.image import ImageCaptcha

image = ImageCaptcha()
app = Flask(__name__)

@app.route("/captcha")
def captcha_view():
    # add your own logic to generate the code
    code = "ABCD"
    data = image.generate(code)
    return Response(data, mimetype="image/png")

Character Settings¶

Added in version 0.6.

Update the default settings to change the character renderring.

from captcha.image import ImageCaptcha

captcha = ImageCaptcha()
captcha.character_rotate = (-40, 40)
captcha.generate("ABCD")

Available options:

character_offset_dx: tuple[int, int] = (0, 4)
character_offset_dy: tuple[int, int] = (0, 6)
character_rotate: tuple[int, int] = (-30, 30)
character_warp_dx: tuple[float, float] = (0.1, 0.3)
character_warp_dy: tuple[float, float] = (0.2, 0.3)
word_space_probability: float = 0.5
word_offset_dx: float = 0.25