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Notes on Sharpening © Davide Barranca. Rev. 1.0.1 - January 2009
1. Introduction
This article is a work in progress collection of personal notes on the subject of sharpening; I’m no digital image processing scientist so, even though I like to play with theoretical problems, I try to find my answers within Photoshop (as I suppose they all do in Dan Margulis’ Color Theory Yahoo group, to which attention I first would like to turn this one). Chances are that I won’t be rigorous too, my aim is to better understand the subject and share my findings with people who would like to integrate them, or simply give a feedback on the techniques exposed. If you’re not interested in all the (very trivial indeed) math and graphs, feel free to skip to the how-to sections: nevertheless, I hope everything will be food for thoughts.
What I'm suggesting with this article is, among the rest, the possibility to target with appropriate sharpening different image features, even if they belongs to the same spatial frequency range (plus an experimental approach to high-radius low-amount sharpening). Then I'm showing how to use bilateral and mixed pyramid decompositions to modulate the sharpening within all the image frequencies.
(Fig. 1.1) Before and after version, applying some of the tecniques exposed in this article.
Un instrumento inmediato y potente para regular el contraste local de una imagen en Photoshop, con un algoritmo que protege las luces altas y las sombras evitando quemaduras y negros sin detalle. La interfaz es simple y limpia: un único cursor permite modular el efecto de manera muy intuitiva.
In 2000, Christian Poulsen, Hasseslblad's current CEO, created a new proprietary format for the Imacon scanners, the Flexible File Format or fff. 3F has determined the bigger revolution in the field of original analog scanning since the introduction of the drum scanners.
Partimos de un concepto muy simple: unir competencias maduradas a partir de experiencias profesionales tradicionales a las posibilidades ofrecidas por las nuevas tecnologías, sobre todo en el campo de la fotografía digital high end que garantiza resultados excepcionales. Trabajamos en Hasselblad digital multidisparo, con resoluciones de hasta 88 millones de pixel a 16 bit que permiten realismo, nitidez y fidelidades cromáticas incomparables.