force download image as response lumen + intervention image

I'm using intervention image on my Lumen project and everything works until I come across on making the encoded image as a downloadable response which upon form submit that contains the image file that will be formatted unto specific format e.g. webp, jpg, png will be sent back as a downloadable file to the user, below is my attempt.

public function image_format(Request $request){
    $this->validate($request, [
        'image' => 'required|file',
    ]);

    $raw_img = $request->file('image');

    $q = (int)$request->input('quality',100);
    $f = $request->input('format','jpg');

    $img = Image::make($raw_img->getRealPath())->encode('webp',$q);

    header('Content-Type: image/webp');

    echo $img;
}

but unfortunately, its not my expected output, it just did display the image.

from this post, I use the code and attempt to achieve my objective

public function image_format(Request $request){
        $this->validate($request, [
            'image' => 'required|file',
        ]);

        $raw_img = $request->file('image');

        $q = (int)$request->input('quality',100);
        $f = $request->input('format','jpg');

        $img = Image::make($raw_img->getRealPath())->encode('webp',$q);
        $headers = [
            'Content-Type' => 'image/webp',
            'Content-Disposition' => 'attachment; filename='. $raw_img->getClientOriginalName().'.webp',
        ];

        $response = new BinaryFileResponse($img, 200 , $headers);
        return $response;
    }

but its not working, instead it showed me this error

any help, ideas please?