Auteur: Jean-Louis Salvignol
Date: 05-09-2006 21:00
Bonsoir Franck
Le plus simple est de reprendre la prose de Lasersoft :
Many of today's scanners allow the ability to write the full dynamic range of its hardware into TIFF-data. This makes the reduction to 24 bit RGB obsolete. The ability to save these 'raw' files opens up a whole new workflow. The images can be scanned and archived into digital format, and then opened at a later date without any loss quality. In order to save such data with extended dynamic range, the 48 bit TIFF format has been defined. Scanners with only 30 or 36 bit capability supply into this format their maximum output. Regardless of the effective dynamic range supplied, the file will always becomes a 48 bit file. Normal scan software saves images into a 24 bit file, discarding the extra information supplied from the scanner. 48 bit files retain all of the information supplied.
Instead of driving the scanner directly, SilverFast HDR enables the user to read these raw files and process the data as if he had access to the original image on the scanner. All SilverFast tools are fully applicable: Defining output size, Auto-Adjust, Histogram, Gradation curves, Selective Color Correction, Unscharp Masking, Color Separation, CMYK-Preview....
1. A sample can be scanned and given back to the customer immediately.
2. Final output processing is not required at this time, the image only has to be saved.
3. Precious samples can be scanned without any loss in quality.
4. The raw scan can be performed by any person (without any knowledge of scanning) – it is only required that the user set the scan resolution.
5. Since the raw scan is now saved in HDR format, it can be transmitted over the internet in this raw form, opening up new dimensions for work flow!
C'est une démarche particulièrement efficiente (pour moi) en N&B, le fichier 16 bits (assez lourd) est un négatif TIFF qui offre un potentiel de travail sous CS2 nettement plus important que les autres options, et notamment de régler les contrastes et les lumières sans faite monter trop vite cet affreux "grain numérique" typique des outils habituels offerts par les logiciels de scan.
En négatif couleur c'est pareil mais plus subtil - trop pour moi qui en fait très peu - mais le process indiqué par Henri Gaud aborde cette affaire du masque orange.
C'est excellent en inversible.
Voyez le site lasersoft.com où il y a des versions de démonstration et pas mal de tuyaux.
JLS
|
|