File uploaded to Amazon S3 displays strange access behavior?

I uploaded the file to my S3 bucket using the AWS SDK for PHP. As a test, I set up a scenario where I pick a file (it is restricted to be an png image), and it is uploaded as test.png. The upload works as there's a file in my bucket called test.png. But instead of opening a page where the image is viewable when I click the link, it initiates a download. The file type says text. After the download, I double click the file and it opens as an image (as it should).

Here is my upload code:

$temp = $_FILES['files']['tmp_name'][0];
require("../vendor/aws/aws-autoloader.php");
$s3 = Aws\S3\S3Client::factory(array(
        'key'    => $aws_access,
        'secret' => $aws_secret
));

$result = $this->db->query('SELECT DEFAULT(`avatar`) FROM (SELECT 1) AS dummy LEFT JOIN users ON True LIMIT 1')->fetchAll()[0][0];
$avatar = $this->session->get('user')['avatar'];

try {
    $result = $s3->putObject(array(
                    'Bucket' => $bucket,
                    'Key' => 'test.png',
                    'SourceFile' => $temp,
                    'ACL' => 'public-read'
    ));

    echo $result['ObjectURL'];
    } catch(Aws\S3\Exception\S3Exception $e)    {
        echo $e->getMessage();
    }
    if($avatar != $result)  {
        // delete current avatar and replace values in session var
    }