Here are two pictures that I took just before heading to the airport. I made a portable calibration target to take with me. It has 8 pieces of polarizer film arranged in steps of 22.5 degrees. No difference can be noticed between them if seen with the naked eye (or a Canon 6D)

However, DOLPi shows the squares encoded by their polarization. Note that the colorbar on the side turns into B&W, showing that DOLPi ignores color, and the color rendering is purely due to polarization