The Kodak article is very interesting. Apparently what you see at 60X
is not the individual grains even though it looks grainy and has a
range of densities. At 400X you can see the individual grains which
appear to be just black. I think the few bits of less dense material
is probably stuff deeper in the emulsion and out of the range of
focus for the microscope.
"When a random pattern of small dots is viewed with sufficient
magnification to resolve the individual dots, no orderly or
intelligible pattern can be recognized. When the magnification is
decreased so the dots cannot be resolved, they appear to blend
together to form an image whose surface is nonuniform or grainy."
So maybe what we are seeing with a grain magnifier is just enough
magnification to see some roughness, but not enough to resolve
A little further down:
"If the uniform dot pattern of a conventional halftone is used to
reproduce a scene, the eye accepts the image as a smooth, continuous-
tone rendition. This happens because the dots are regularly spaced.
However, when halftone dots are distributed randomly in an area to
reproduce a changing scene the image looks "grainy." Graininess in
the image is due, in part, to the random distribution of the
individual elements which make up that moving image."
That would seem to be an argument for the regular grid array of a
sensor, unless it is generating random electronic noise. :-)
Long Beach, California, USA
On Mar 13, 2006, at 8:21 AM, Piers Hemy wrote:
> Does this page
> exposureP.shtml help
> (starting about half-way down the page, some images of grain,
> including a
> SEM image)?
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