使用HttpRequest发送Imagick图像（POST）

How can I send an imagic-image with http post without writing image to a disk? The code below isn't working.

 // function returns an Imagick Object
    $image = $this->generateLvlImage($avatarUrl, $lvl);

    // I want to send it with http post
    $postRequest = new \HttpRequest($uploadUrl, \HttpRequest::METH_POST);
    $postRequest->addRawPostData('photo='.(string)$image);
    try {
        $postRequest->send();
        if ($postRequest->getResponseCode() === 200) {
            $response = $postRequest->getResponseBody();
        } else {
            throw new \Exception('post.failed');
        }
    } catch (\HttpException $e) {
        throw new \Exception($e->getMessage());
    }

It's really hard to say for sure without knowing exactly who/what you're attempting to submit it to. Typically, you would base64_encode the image and then base64_decode it on the other end.

$postRequest->addRawPostData('photo='.base64_encode($image->getImageBlob()));

Edit: If you want to send it via multi-part form data then I couldn't give you an answer without plagiarising someoneelses work, so here is a tutorial on it: http://blog.cloudspokes.com/2013/01/reblog-post-multipartform-data-with.html