Paleonet: Orthochromatic images
PATRICIO DOMINGUEZ ALONSO
patricio at geo.ucm.es
Wed Mar 23 12:03:48 GMT 2011
Use a blue filter
----- 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
> ...and some of my dioramas at FossiliVeraciand Paleonet
Dr. Patricio DOMINGUEZ
Dep. Paleontologia. Fac. Ciencias Geologicas.
Universidad Complutense de Madrid
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