Nonac_eos' photostream  

My Blog: extendedphotography.blogspot.com/






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Just trying to get decent shots! Is not that easy..

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Actually I am trying to understand and (maybe one day) master the HDRI (High Dynamic Range Imaging) tecnique.

This photographic tecnique was born in order to be able to cover and capture the entire dynamic range (the light difference between the darkest shadow and the strongest highlight) of any lighting condition by means of conventional digital photographic equipments.

At the present time one of the most important application of HDR pictures is the recreation of realistic lighting conditions on virtual 3D model in computer graphics.

The second one is purely photographic and has lead to two main approaches to the tecnique: the realistic and the surrealistic HDR. But before starting to explain the differences between this two approaches it is necessary to spend two words on the typical HDR workflow: (to be continued).

Nowaday the use of HDRI tecnique is at the same time trend, art and abuse as well. In my opinion the big mass is able to mortify the true sense of this form of photography through unconscious experimentation and delibarate impressionistic representations of the reality.
Fortunately a ristrected number of photographers/artists has been able to express the true potential of this tecnique with the porpuse of mimiquing the human eye perception of reality.

Did you know that:

1) real HDR picture (.hdr, .exr, files) cannot be displayed on common tv an pc screens (8bit color depht)? The in flickr (or other foto-sharing websites) commonly as HDR tagged pictures are in reality (hopefully) tone-mapped HDR files or (in worst case) tone-mapped RAW files.

2) HDR cannot be generated by a single RAW file? The tone-mapping of a RAW file allows to recover detail from the shadows areas (thanks to the 12 or 14bit colour depht per channel of RAW files) but you will never be able to cover the tipical dynamic range of a HDR file of 14-16 EV (exposure value: an increase/decrease of 1 EV correspond to a doubling / halving of the light "exposing" your sensor or film).

3) that an HDR file (or picture) in contrast to a jpeg (8bit without exif data) contains phisically related luminance (cd/m^2) values? Therefore it is possible to perform radiometric measurements, or in other words it is possible to derive the quantity of light coming from reflecting surface.

4) that our eye reacts to light by means of two mechanisms: (1) non-linear sensibility, (2) Local adaptation

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Interesting Photography Books

1) Das HDRI-Handbuch; High Dynamic Range Imaging für Fotografen und Computergrafiker; Christian Bloch

2) Understandin Exposure; How to Shoot Great Photographs with A Film or Digital Camera; Brian Peterson

3) Creative Nature & Outdoor Photography; Brenda Tharp

4) Photographic Composition; Guidlines For Total Image Control Through Effective Design; Tom Grill & Mark Scanlon

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