Unfortunately, there are not many common terms shared between filtering/validating/etc. libraries. To clear up misconception, this library uses the following definitions:
"filter": validate and/or sanitize one or more fields
"validate": determine if a field value conforms to a particular format, but do not modify the field value
"sanitize": modify, transform, or otherwise force a field value to conform to a particular format
This library also makes a distinction between a "value" filter and a "subject" filter:
A "value" filter validates and sanitizes an individual value
A "subject" filter validates and sanitzes the collection of elements in an array, or the collection of properties in an object. (The "subject" is the array or object.)
The easiest way to interact with the filter system is via the FilterFactory. Instantiate it first; you can then get filter objects from it:
use Aura\Filter\FilterFactory;
$filter_factory = new FilterFactory();
$filter = $filter_factory->newValueFilter();
$filter = $filter_factory->newSubjectFilter();