{
     ...,
     "avatar": "http://example.com/my/image/path/image_name.png",
     ....
}

{
    ...,
    "icon": "http://example.com/my/image/path/another_image_name.png",
    ...
}

(For User instance)
{
    ...,
    "name": "http://example.com/my/image/path/image_name.png",
    ...
}

(For Application instance)
{
    ...,
    "name": "http://example.com/my/image/path/another_image_name.png",
    ...
}

//srcAppBundleEntityUser.php
//...
/**
 * @var integer
 *
 * @ORMOneToOne(targetEntity="AppBundleEntityImage")
 * @ORMJoinColumn(name="avatar", referencedColumnName="id")
 *
 * @JMSExpose()
 * @JMSType("Image")
 */
private $avatar;
//...

//srcAppBundleEntityApplication.php
//...
/**
 * @var integer
 *
 * @ORMOneToOne(targetEntity="AppBundleEntityImage")
 * @ORMJoinColumn(name="icon", referencedColumnName="id")
 *
 * @JMSExpose()
 * @JMSType("Image")
 */
private $icon;
//...

<?php
//srcAppBundleSerializerImageTypeHandler.php
namespace AppBundleSerializer;


use AppBundleEntityImage;
use JMSSerializerContext;
use JMSSerializerGraphNavigator;
use JMSSerializerHandlerSubscribingHandlerInterface;
use JMSSerializerJsonSerializationVisitor;
use SymfonyComponentHttpFoundationRequest;

class ImageTypeHandler implements SubscribingHandlerInterface
{
    private $request;

    public function __construct(Request $request) {
        $this->request = $request;

    }

    static public function getSubscribingMethods()
    {
        return [
            [
                'direction' => GraphNavigator::DIRECTION_SERIALIZATION,
                'format' => 'json',
                'type' => 'Image',
                'method' => 'serializeImageToWebPath'
            ]
        ];
    }

    public function serializeImageToWebPath(JsonSerializationVisitor $visitor, Image $image = null, array $type, Context $context)
    {
        $path = $image ? "http://" . $this->request->getHost() . "/uploads/images/" . $image->getPath() : '';

        return $path;
    }
}

app.image_type_handler:
    class: AppBundleSerializerImageTypeHandler
    arguments: ["@request"]
    scope: request
    tags:
        - { name: jms_serializer.subscribing_handler }