.
If one expects a certain result
one may experience an unexpected result
In front of me a keyboard,
above that a monitor on which
[ "In front of me... "]
To my right a mouse,
to my left a scanner/
HA HA
From time to time I give some thought to the shadow cast by the scanner's light as it moves from one end of its field to the other.
If a sheet of black material is placed over an object-to-be-scanned then the scanned image will appear with a black background. Similarly, if a white cover is used a white background is the result.
However, if one does use a white background the scanner's light will cast a shadow from the-object-being-scanned onto the white field. Even from a white-on-white paper's edge.
Sometimes this shadow is inconvenient, and to remove or obviate it can require a deal of secondary scanning : after the first scan the object is rotated 180 degrees and then re-scanned from the other direction, as it were. The shadows are then absent from their original locations but appear instead at the opposite, previously shadowless edges. These two scans from opposite directions are then melded and finessed to exclude any unwanted shadow.
It had occurred to me that one might be able to achieve a shadowless image in a single pass if a mirror, instead of a sheet of white paper, was placed over the object-to-be-scanned. Again some observations: if one places no cover over the object-to-be-scanned, that is if one leaves the flatbed scanner lid open, then usually the resultant scan shows an unfocused dull background or, if the room is dark, a black background behind the object scanned. And, to reiterate, if one uses a white background cover one gets a white background scan.
Putting these observations together I imagined that a sheet of mirror laid onto the scanner bed would reflect back and thus digitally picture the scanner's own bright white light. The only problem anticipated was that the light, being so relatively bright, might appear to bleed or fog a little around the edges of the object-to-be-scanned. I certainly did not anticipate
this result:
The image above is a screen snap of the preview scan (and the actual scan produced the same) : upon the scanner's glass is the unearthed corroded label, the intended object-to-be-scanned; around that, plus some, the 'marching ants' frame that indicates the area to be scanned; within that, as well as the old label, appears a blue finger print. The latter certainly provides a clue or two (including from the
Tyndall Effect) as to why the background appears as black rather than the white I expected.
The scanner's recorder of evidence appears to respond only to a partial return of its search light, as with the dis-scribed Label and the greasy finger mark, but not to recognise the light's total unmediated return from the surface of the selfless mirror.
Light from the Sun reveals the Moon to our eyes. If beside the illuminated Moon there also orbited a vast flat mirror, and if that mirror was angled correctly would we not see the bright light of the Sun reflected to illuminate our stardust bodies as well? Just how eye-like is a camera or scanner? We know we must not look directly at the Sun: it's radiance is too intense for our jelly optics and can destroy our sight. Rather, we must observe it indirectly, as it illuminates our surrounds. (Moses returns from the mountain, unconscious of his blinding luminescence, and is asked to wear a veil.) Lost in fact, adrift in analogy, feeling primitive.
This familiar and ancient speculation set: a source of light; something to be shone upon; the shadow component too; a cave wall projection-theatre; a mirror; some labels; the ____; a ____; observer/s...
