Edit in JSFiddle

var app = angular.module('app', []);

app.filter('makeUppercase', function () {
    return function (item) {
        return item.toUpperCase();
    };
});

app.controller('PersonCtrl', function () {
    this.username = 'Todd Motto';
});

<div ng-app="app">
    <div ng-controller="PersonCtrl as person">
        <p>
            {{ person.username | makeUppercase }}
        </p>
    </div>
</div>