Currently the Change Filters-process action works with static values and ‘Equals’, as stated in the documentation:
The filter value that must be set on the column in question as an equal to filter condition. This parameter is present for every column of the subject.
It would be nice if there are more options, like ‘is not empty’, ‘starts with’ etc, just like the normal Filter function.
Actually, a few lines earlier in the documentation it states: “It can be indicated for each column which filter condition and which filter value must be used.”