Craft\ImagerService::_vignette PHP Method

    private function _vignette($imagickInstance, $color1 = 'none', $color2 = 'black', $crop_factor = 1.5)
    {
        $vignetteWidth = floor($imagickInstance->getImageWidth() * $crop_factor);
        $vignetteHeight = floor($imagickInstance->getImageHeight() * $crop_factor);
        $radial = new \Imagick();
        $radial->newPseudoImage($vignetteWidth, $vignetteHeight, "radial-gradient:{$color1}-{$color2}");
        $radial->setImageFormat('png32');
        $imagickInstance->compositeImage($radial, \imagick::COMPOSITE_MULTIPLY, -($vignetteWidth - $imagickInstance->getImageWidth()) / 2, -($vignetteHeight - $imagickInstance->getImageHeight()) / 2);
    }