Grafika\Gd\Filter\Contrast::apply PHP Method

public apply ( Image $image ) : Image
$image	Grafika\Gd\Image
return	Grafika\Gd\Image

    public function apply($image)
    {
        imagefilter($image->getCore(), IMG_FILTER_CONTRAST, $this->amount * -1);
        return $image;
    }

Contrast