Miscellaneous Imaging Methods
Two kinds of thermocameras were tested, using short (2-5µ m;
Inframetrics) and long wavelenghts (8-12µ m; Agema).
These kinds of infrared cameras record the temperature
variations on surfaces. The papyri
background and the writing could have slightly different
emissivities, or they could absorb heat in slightly
different manners. Unfortunately the glass plate is
not translucent in these infrared wavelengths, so that the
cameras could only record the temperatures of the glass
surface itself (with the fingerprints upon it).
X-ray equipment had a similar problem with the glass plate as
did the thermocameras. The plate was taken to Helsinki Central
University Hospital, and tested with varied energies, exposure
times and intensities. With 12 bits of grayscale depth nothing was
Stereographic imaging was supposed to find the depth variances
of the writing with respect to the surface. It is known that when
one writes upon a stack of papers, the writing can be deduced
from several sheets below from the small grooves caused by the
pressure of the pencil. If the papyri material were soft enough,
the untouched surface should be a little higher than the areas
A stereographic microscope was used to observe the supposed
minuscule variations in depth. With large magnification, the fibers
of the papyri were clearly visible, and the structure was identifiable
to one of a plant. Unfortunately, this method did not reveal any
detectable depth differences from the characters.
Although the script isn't lower than the background, the
magnification and depth effect of a stereomicroscope helps
discriminating other black marks in the background from the script.
The black marks are usually caused by special surface structure,
such as crevices and small cracks, and are easaily identifiable
with a stereomicroscope.
To avoid the limitation of the straight angles needed in
photography, live video recordings were made from a session
of studying the plate.
By moving and turning,
different areas of the writing can be found easier to read.
Photography cannot do that. The only way to record this would be
taking the whole process to video. There is at least one problem:
the viewer cannot follow the thoughts of the recorder, and it
is not intrinsically clear where the point of interest is going
to be, and thereby the viewer may frustrate quickly.
If the recorder controls his/her actions by rehearcing his/hers
movements, masters the camera techniques (proper focusing etc.)
correctly and moves the plate always slowly, this could be avoided.
The rotation and movement of a plate gives a wholly new
angle in perception. The human eye sees more than a series
of pictures; we see a flow with no interrupts, and can
automatically detect different dynamical visual properties.
For example, while rotating a plate, the background may
fade from one shade of gray to another in a different way
compared to the text. Grabbing scenes from a video session
would produce a series of pictures which highlight different
parts of texts, but the dynamics of motion would be less
In principle, a sequence of frames contains more information
than any corresponding single frame. A completely another story
is how to benefit from this information. Further tests are
recommended to find suitable patterns of movement and rotation
to record. The live video recordings could at least be
used as demonstrations of the importance of illumination and
nature of the plates.
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Antti Nurminen, 34044T, email@example.com