Contrast Transfer Function (CTF) Analysis Tool

We present an automated analysis tool designed to generate reproducible Contrast Transfer Functions (CTFs) for various types of Head-Mounted  Displays (HMDs). This CTF analysis tool processes acquired images from the HMD display. To compute the CTF of the HMD, a grille pattern with alternating black and white bars of equal width (either in the vertical or horizontal direction) is displayed on the HMD screen. The varying  widths of these bars correspond to different spatial frequency values, representing cycles per degree, which allow for the measurement of  Michelson contrast at these spatial frequencies. This tool is developed as a general method that can be applied to a wide variety of HMDs,  encompassing different design and display technologies, enabling the generation of reproducible CTFs.

Installation
1-Download the installer file: CTF Tool Installer.exe.
2-Run the installer and follow the on-screen instructions to complete the installation.

Usage Instructions
A User Manual is available, which includes installation steps and detailed usage instructions. 
Please refer to the manual for guidance on how to use the tool effectively.

Contact Support
If you encounter issues not covered in this manual or need further assistance, please contact our support team at: RST_CDRH@fda.hhs.gov.

Related Links
[1] “IEC 63145-20-20:2019 Eyewear display - Part 20-20: Fundamental measurement methods - Image quality,” (2020).
[2] “Information Display Measurement Standards (IDMS), Society for Information Display (SID), Video Electronics Standards Association (VESA), International Committee for Display Metrology (ICDM),” (2023).
[3] Beams, R., Brown, E., Cheng, W.-C., Joyner, J. S., Kim, A. S., Kontson, K., Amiras, D., Baeuerle, T., Greenleaf, W., Grossmann, R. J.,et al., “Evaluation challenges for the application of extended reality devices in medicine,” Journal of Digital Imaging 35(5), 1409–1418 (2022).
[4] Draper, R. S., Penczek, J., Varshneya, R., and Boynton, P. A., “72-2: Standardizing fundamental criteria for near eye display optical  measurements: Determining eye point position,” in [SID Symposium Digest of Technical Papers], 49(1), 961–964, Wiley Online Library (2018).
[5] Austin, R. L., Denning, B. S., Drews, B. C., Fedoriouk, V. B., and Calpito, R. C., “Qualified viewing space determination of near-eye and head-up displays,” Journal of the Society for Information Display 26(9), 567–575 (2018).
[6] Winters, D., Ruprecht, A., Erichsen, P., Yadav, M., Eggers, J.-H., and Stauss, B., “82-3: Optical quality requirements for accurate mtf/ctf measurements on near-eye-displays,” in [SID Symposium Digest of Technical Papers], 55(1), 1147–1150, Wiley Online Library (2024).
[7] Bader, A. M., Badano, A., and Beams, R., “Quadrant detector-based method for eye point alignment of augmented and virtual reality head mounted displays,” in [Optical architectures for displays and sensing in augmented, virtual, and mixed reality (AR, VR, MR) III ], 11931, 82–88, SPIE (2022).

Disclaimer
This software and documentation were developed at the Food and Drug Administration (FDA) by employees of the Federal Government in the course of their official duties. Pursuant to Title 17, Section 105 of the United States Code, this work is not subject to copyright protection and is in the public domain. Permission is hereby granted, free of charge, to any person obtaining a copy of the Software, to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, or sell copies of  the Software or derivatives, and to permit persons to whom the Software is furnished to do so. FDA assumes no responsibility whatsoever for  use by other parties of the Software, its source code, documentation or compiled executables, and makes no guarantees, expressed or implied, about its quality, reliability, or any other characteristic. Further, use of this code in no way implies endorsement by the FDA or confers any advantage in regulatory decisions. Although this software can be redistributed and/or modified freely, we ask that any derivative works  bear some notice that they are derived from it, and any modified versions bear some notice that they have been modified.