Angular Factory - Altering Returned Data

I'm following along on the Angular JS Tutorial and I was wondering if there is an alternate approach to how I'm modifying it.

Currently, I am returning data with a factory that is defined as such:

angular.
    module('core.card').
    factory('Card', ['$resource',
        function($resource){
            return $resource('cards/:cardId.json', {}, {
                query: {
                    method: 'GET',
                    params: {cardId: 'cards'},
                    isArray: true
                }
            });
        }
    ]);

This is all good and working, as cards.json has all of the cards available and that's exactly what I want to return.

The method that they're describing, such as dealing with a RESTful service, assumes that there are multiple other specific JSON files that could get returned based on the route. I understand how to use that with an actual service, but let's say I wanted to alter the returned JSON data before it gets bound to my module so I don't have a bunch of extra data that I don't need?

Lets say /cards/foo.json contains something like this:

[{
    "id": "foo",
    "name": "Bar",
    "img": "foobar.png",
    "unnecessaryKey": "remove me"
}]

But where would I write a function that only returns:

[{
    "id": "foo",
    "name": "Bar",
    "img": "foobar.png"
}]

Would I assign it in the same place where the query function is, such as:

        ...
        return $resource('cards/:cardId.json', {}, {
            query: {
                method: 'GET',
                params: {cardId: 'cards'},
                isArray: true
            },
            alterReturnedData: {
                // doStuffToFormatData
            }
        });
        ...

Or would it be best to just modify it in my Component as I'm doing now?

function alterReturnedData(data){
    // doStuffToFormatData
}
var unmodified = Card.get({cardId:'foo'}, function(){
    self.data = alterReturnedData(unmodified);
});

I just feel like it'd be better to return the data from the Service I actually want to the Component Controller instead of having a lot of logic in there to skew it around.

Is my approach OK to run this function in the Controller? Or is it best to alter it in the Service, and how would I do so?