Yes, it is possible to use variable from the $scope
See this fiddle for an example:
http://jsfiddle.net/lopisan/Kx4Tq/
HTML:
<body ng-app="myApp">
<div ng-controller="MyCtrl">
<input ng-model="variable"/><br/>
Live output: {{variable | countmessage : type}}!<br/>
Output: {{1 | countmessage : type}}!
</div>
</body>
JavaScript:
var myApp = angular.module('myApp',['myApp.filters']);
function MyCtrl($scope) {
$scope.type="cat";
}
angular.module('myApp.filters', [])
.filter('countmessage', function () {
return function (input, itemType) {
var result = input + ' ' + itemType;
if (input > 1) result += 's';
return result;
}
});