Paleonet: Orthochromatic images

PATRICIO DOMINGUEZ ALONSO patricio at geo.ucm.es
Wed Mar 23 12:03:48 GMT 2011


Use a blue filter

Patricio

----- Mensaje original -----
De: enrico bonino <e_bonino at yahoo.it>
Fecha: Miércoles, Marzo 23, 2011 12:55
Asunto: Paleonet: Orthochromatic images
A: PaleoNet <paleonet at nhm.ac.uk>

> Dear all
> 
> I'm searching for a method that allow to acquire images with a 
> digital camera (Fujifilm filmpix S2Pro) that can emulate the old 
> Orthochromatic films.
> 
> Orthochromatic films block the red wavelength and are sensitive 
> to blue and green only, giving a great contrast when red colors 
> are present in the image. 
> 
> 
> These films are used in Xiangguang & Bergström  (1997), 
> Arthropods of the Lower Cambrian Chengjiang fauna, southwest 
> China, in Fossils & Strata n°45, to improve the contrast of some 
> lower Cambrian Chengjiang arthropods.
> This methods don't need the immersion of the sample in Toluene 
> or Xylene alcohols, and it is very useful when the matrix (and 
> this is the case) is soft, like marls and clays.
> 
> 
> Chengjiang fossils are generally covered by a thin Iron oxide 
> layer, and this technique allow to increase the contrast between 
> the gray-yellow matrix and the reddish fossil.
> 
> Looking at some filters that have the same spectral  behavior, 
> I've found that the cyan Kodak Wratten gelatine filters 44 and 
> 44A (http://en.wikipedia.org/wiki/Wratten_number and 
> http://www.physics.uc.edu/~sitko/LightColor/4-ColorMix/ColorMixing_files/image026.png for the transmittance curve) are able to give the nearly same result of the old and practically unavailable orthochromatic films. 
> 
> 
> There is someone that has developed similar techniques and 
> digital image processing methods to increase the contrast using 
> peculiar filters?
> 
> Thank you,
> 
> Enrico Bonino
> 
> *********************
> Enrico Bonino Dr.
> GIS Specialist - Geologist at KEYOBS SA, Liège, Belgium
> Museum Curator at the Back to the Past Museum, Cancun, Mexico
> skype: enrico_bonino
> http://www.backtothepast.com.mx
> http://www.keyobs.com/fr/ebonino
> ...and some of my dioramas at FossiliVeraciand Paleonet
> *********************
> 
> 
>       

__
Dr. Patricio DOMINGUEZ
Dep. Paleontologia. Fac. Ciencias Geologicas. 
Universidad Complutense de Madrid


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