Improving the sensitometric and OECF standards: recognizing the photosensitive exposure range

Michael G. Prais

doi:10.1117/12.871549

24 January 2011 Improving the sensitometric and OECF standards: recognizing the photosensitive exposure range

Michael G. Prais

Proceedings Volume 7876, Digital Photography VII; 78760T (2011) https://doi.org/10.1117/12.871549
Event: IS&T/SPIE Electronic Imaging, 2011, San Francisco Airport, California, United States

Abstract

This article demonstrates that and how sensitometric and opto-electronic characteristic function (OECF) standards should be changed: The sensitivity S of all photosensitive arrays is--and, in standards, should be--determined by the midtone photosensitive exposure of the array Hmid, the binary logarithm of which is [log₂(H_max) + log₂(Hmin)]/2. The reference exposure H_o = S/H_sp of a photosensitive array is--and, in standards, should be--determined by the width of the photosensitive exposure range Δ, which is determined by the measured minimum and maximum usable photosensitive exposures, H_max and H_min. Knowledge of H_max and H_min (or H_mid and Δ) makes the reference exposure H_o, the speed point exposure H_sp and the safety factor σ unnecessary, and these extraneous quantities should be eliminated from the sensitometric standards. In addition, the sensitometric standard for solid-state arrays, ISO 12232-2006, and the OECF standard, ISO 14524-1999, should be changed because they use a photosensitive exposure range which is inappropriate for solid-state arrays. Finally, this article shows that all current standards establish midtone reflectances R_mid for standard photosensitive arrays that are much less than oft-touted 18% making most references to 18% inappropriate.

Citation Download Citation

Michael G. Prais "Improving the sensitometric and OECF standards: recognizing the photosensitive exposure range", Proc. SPIE 7876, Digital Photography VII, 78760T (24 January 2011); https://doi.org/10.1117/12.871549

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available