> > If you take 3 sonsecutive photographs through a red, a blue and a
> >green filter, the resulting pictures can be used to reproduce the original
> >colours of the subject. Taht's the principle of colour separation as it's
> >used in the offset procedure, for example.
> >
> > Now I wonder what happened if you took 2 or 3 X-Ray photographs
> >through a same object, interposing successively 2 or 3 sheet of different
> >opaque materials. Could these radiographs be used to elaborate a coloured
> >picture, which would permit the optical distinction of different materials?
> >
> Now that is a very interesting question. I play around making
> cyanotypes, e.g., from x rays but have never of course tried color
> separations...one would have to get the hospital to allow one to put on
> filters....and I wonder if color filters on xrays would work the same as
> with regular light specrta. Love to hear about your experience with it.
> karl Koenig
Good point here, in my reply I assumed that the 2 or 3 sheets of
different (X-Ray) opaque materials would act as neutral density
filters to the X-Rays. I don't think this is necessarily true.
These materials could just as easily act as selective X-ray
wavelength filters (the colours of X-rays). I suspect a lot of
research and experimentation would be needed to get control of this.
I am pretty sure that colour filters (e.g. gelatin filters) as used
for visible light would be useless for this. They would be totaly
transparent to the X-rays. Aluminized mylar or those fancy colours
of partial mirror-glass that use different metals would be a better
place to start (the research not the experimentation:-)
Other points to consider are what is the spectrum of the X-ray
source? and what is the sensitivity spectrum of the film to that
range of X-ray wavelengths.
Sandor Mathe -- sandor.mathe@prior.ca
(905) 670-1225 x333
FAX (905) 670-1344