$transparent public property Whether to use transparent background. Defaults to false. public boolean $transparent = false

$offset public property The offset between characters. Defaults to -2. You can adjust this property in order to decrease or increase the readability of the captcha. public integer $offset = -2

$maxLength public property The maximum length for randomly generated word. Defaults to 7. public integer $maxLength = 7

$minLength public property The minimum length for randomly generated word. Defaults to 6. public integer $minLength = 6

$padding public property Padding around the text. Defaults to 2. public integer $padding = 2

$fixedVerifyCode public property The fixed verification code. When this property is set, getVerifyCode() will always return the value of this property. This is mainly used in automated tests where we want to be able to reproduce the same verification code each time we run the tests. If not set, it means the verification code will be randomly generated. public string $fixedVerifyCode = null

$fontFile public property The TrueType font file. This can be either a file path or path alias. public string $fontFile = '@yii/captcha/SpicyRice.ttf'

$imageLibrary public property (available since version 2.0.7) The rendering library to use. Currently supported only 'gd' and 'imagick'. If not set, library will be determined automatically. public string $imageLibrary = null

$foreColor public property The font color. For example, 0x55FF00. Defaults to 0x2040A0 (blue color). public integer $foreColor = 2113696

$height public property The height of the generated CAPTCHA image. Defaults to 50. public integer $height = 50