Wear track measurements

I am trying to measure with a Profilm3D a series of wear tracks generated by linear reciprocating wear tests on polished titanium surfaces. The resulting images from the profilometer (regardless of the length and backscan values) show a gray background in the wear track, as if it is not detecting the worn surface. Although there is a possibility of oxide formation, the amount cannot be so large as to limit the data collection from the wear track surface. Is there any way to solve this problem? Should I use specific parameters?