How to get image file from public folder as a response in Laravel?

These are different ways I have tried in my controller to get image as response.

My images resides in public folder/img.

switch ($document->ext) {

    case 'doc':
        $img = File::get(url('/img/doc.png'));
        break;

    case 'docx':
        $img = File::get(asset('/img/docx.jpg'));
        break;

    case 'pdf':
        $img = File::get(public_path('/img/pdf.png'));
        break;

    case 'ppt':
        $img = File::get(url(public_path('/img/ppt.png')));
        break;

    default:
}
return new Response($img, 200);