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Proceedings Paper

The Ansel Adams zone system: HDR capture and range compression by chemical processing
Author(s): John J. McCann
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Paper Abstract

We tend to think of digital imaging and the tools of PhotoshopTM as a new phenomenon in imaging. We are also familiar with multiple-exposure HDR techniques intended to capture a wider range of scene information, than conventional film photography. We know about tone-scale adjustments to make better pictures. We tend to think of everyday, consumer, silver-halide photography as a fixed window of scene capture with a limited, standard range of response. This description of photography is certainly true, between 1950 and 2000, for instant films and negatives processed at the drugstore. These systems had fixed dynamic range and fixed tone-scale response to light. All pixels in the film have the same response to light, so the same light exposure from different pixels was rendered as the same film density. Ansel Adams, along with Fred Archer, formulated the Zone System, staring in 1940. It was earlier than the trillions of consumer photos in the second half of the 20th century, yet it was much more sophisticated than today's digital techniques. This talk will describe the chemical mechanisms of the zone system in the parlance of digital image processing. It will describe the Zone System's chemical techniques for image synthesis. It also discusses dodging and burning techniques to fit the HDR scene into the LDR print. Although current HDR imaging shares some of the Zone System's achievements, it usually does not achieve all of them.

Paper Details

Date Published: 17 February 2010
PDF: 10 pages
Proc. SPIE 7527, Human Vision and Electronic Imaging XV, 75270S (17 February 2010); doi: 10.1117/12.844972
Show Author Affiliations
John J. McCann, McCann Imaging (United States)


Published in SPIE Proceedings Vol. 7527:
Human Vision and Electronic Imaging XV
Bernice E. Rogowitz; Thrasyvoulos N. Pappas, Editor(s)

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