The coordinates may be integer valued, but are not stored in an integer datatype. You can see this if you do the following:
>> class(m)
I'd expect you to see double as the result. In order to use the MarkerInserter, points are expected to be of an integer datatype, namely one of the following: uint8, uint16, uint32, uint64, int8, int16, int32 or int64.
So, you can convert the matrix indices to an integer type:
J = step(markerInserter,bw,uint32([m n]));
Hope this helps!
