A predetermined test sample is used to test a measuring instrument for gravimetric moisture determination. The crystal wedge spatially separates an input optical signal into a first beam component having a first polarization state and a second beam component having a second polarization state. The film can be formed on a flexible, removable substrate. The polypropylene addition provides the drawstring with improved modulus or stiffness and improved tensile yield. The subsequent video images are enhanced based on the one or more transformed positions.