How get content of image using ob_get_contents

Question

I'd like to get the content of the file from imagePng(), on my code, it returns empty.

Just for a test, if I remove the ob_end_clean() and it's printing the content but I don't know how can I getting it. I guess I'm missing something in my code.

public function create_thumb($content_file, $percent=5){

        $result = array(
            'success'   => true,
            );

        list($width, $height)  = @getimagesize($content_file);
        $n_width  = $width * $percent;
        $n_height = $height * $percent;
        $image_src = @imageCreateFromPng($content_file);

        if($image_src){

            ob_start();

            $image = @imagecreatetruecolor($n_width, $n_height);
            @imagecopyresampled($image, $image_src, 0, 0, 0, 0, $n_width, $n_height, $width, $height);
            @imagepng($image, null, 100);
            $result['thumb'] = ob_get_contents();
            ob_end_clean();
        }else{
            $result['success'] = false;
            $result['image_src'] = $image_src;
        }


        return $result;
    }

My Return:

{
      "success": true,
      "thumb": {
        "success": true,
        "thumb": ""
      }
 }

Solution

It was missing base64_encode(ob_get_contents()) on my code.

ob_start();
@imagepng($image, null, 100);
$result['thumb']  = 'data:image/png;base64,' . base64_encode(ob_get_contents())
ob_end_clean();