Grafika\Grafika::createFilter PHP Method

    public static function createFilter($filterName)
    {
        $editorName = self::detectAvailableEditor();
        $p = func_get_args();
        if ('Imagick' === $editorName) {
            switch ($filterName) {
                case 'Blur':
                    return new ImagickBlur(array_key_exists(1, $p) ? $p[1] : 1);
                case 'Brightness':
                    return new ImagickBrightness($p[1]);
                case 'Colorize':
                    return new ImagickColorize($p[1], $p[2], $p[3]);
                case 'Contrast':
                    return new ImagickContrast($p[1]);
                case 'Dither':
                    return new ImagickDither($p[1]);
                case 'Gamma':
                    return new ImagickGamma($p[1]);
                case 'Grayscale':
                    return new ImagickGrayscale();
                case 'Invert':
                    return new ImagickInvert();
                case 'Pixelate':
                    return new ImagickPixelate($p[1]);
                case 'Sharpen':
                    return new ImagickSharpen($p[1]);
                case 'Sobel':
                    return new ImagickSobel();
            }
            throw new \Exception('Invalid filter name.');
        } else {
            switch ($filterName) {
                case 'Blur':
                    return new GdBlur(array_key_exists(1, $p) ? $p[1] : 1);
                case 'Brightness':
                    return new GdBrightness($p[1]);
                case 'Colorize':
                    return new GdColorize($p[1], $p[2], $p[3]);
                case 'Contrast':
                    return new GdContrast($p[1]);
                case 'Dither':
                    return new GdDither($p[1]);
                case 'Gamma':
                    return new GdGamma($p[1]);
                case 'Grayscale':
                    return new GdGrayscale();
                case 'Invert':
                    return new GdInvert();
                case 'Pixelate':
                    return new GdPixelate($p[1]);
                case 'Sharpen':
                    return new GdSharpen($p[1]);
                case 'Sobel':
                    return new GdSobel();
            }
            throw new \Exception('Invalid filter name.');
        }
    }