Linearization and Normalization in Spatial Frequency Response Measurement

The standard ISO12233:2014 describes different methods on how to measure the spatial frequency response (SFR) of an imaging system. It uses either a slanted edge (eSFR) or a harmonic Siemens star (sSFR). Within the document, it is mentioned that a linearization process shall correct a non-linear tone curve. Normalization is not further defined, but is an important part of the evaluation for the sSFR method.

Using the sSFR method for texture loss analysis in the upcoming ISO19567 standard (based on a low contrast version of the Siemens star) it is even more critical. In this paper, we evaluate the influence of linearization and normalization on the results, identify issues in common implementations and present a new approach.