How to use sensor_msgs/Image shared pointer in nodelets?

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Hi,

I have a nodelet that uses a custom service, called PushImage, of type:

sensor_msgs/Image image
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Basically, the nodelet will receive the image and store the data within itself.

I understand that nodelets offer the advantage of zero-cost transport of data, IF they use shared pointers. Will my nodelet benefit from this zero-cost transport with a message of this type? Is there something special I have to do to make sure my nodelet is using a shared pointer? Here is my current callback to the PushImage service:

pushImageCB(custom_messages::PushImage::Request& req, custom_messages::PushImage::Response& resp)