CaptchaBundle/Resources/config/services.yml

services:
    # captcha type
    captcha.type:
        class: Gregwar\CaptchaBundle\Type\CaptchaType
        arguments: [ "@session", %gregwar_captcha.width%, %gregwar_captcha.height%, %gregwar_captcha.length%, %gregwar_captcha.as_file%, %gregwar_captcha.image_folder%, %gregwar_captcha.web_path%, %gregwar_captcha.gc_freq%, %gregwar_captcha.expiration% ]
        tags:
            - { name: form.type, alias: captcha }