captcha.php

<?php

return [

    'characters' => '2346789abcdefghjmnpqrtuxyzABCDEFGHJMNPQRTUXYZ',

    'default' => [
        'length'  => 4,
        'width'   => 120,
        'height'  => 36,
        'quality' => 100,
    ],

    'flat' => [
        'length'     => 4,
        'width'      => 250,
        'height'     => 76,
        'quality'    => 100,
        'lines'      => 12,
        'bgImage'    => false,
        'bgColor'    => '#ecf2f4',
        'fontColors' => ['#2c3e50', '#c0392b', '#16a085', '#c0392b', '#8e44ad', '#303f9f', '#f57c00', '#795548'],
        'contrast'   => -5,
    ],

    'mini' => [
        'length' => 3,
        'width'  => 60,
        'height' => 32,
    ],

    'inverse' => [
        'length'    => 5,
        'width'     => 120,
        'height'    => 36,
        'quality'   => 90,
        'sensitive' => true,
        'angle'     => 12,
        'sharpen'   => 10,
        'blur'      => 2,
        'invert'    => true,
        'contrast'  => -5,
    ]

];