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GRAHAM THOMAS JOHNSON <[log in to unmask]>
Reply To:
SciArt-L Discussion List-for Natural Science Illustration- <[log in to unmask]>
Tue, 25 Nov 1997 00:46:30 -0500
TEXT/PLAIN (46 lines)
I've used a similar technique to illustrate small fossil teeth.  I mount
teeth of similar sizes onto a board using clay.  I then suspend the board
over my scanner using magazines on each side.  I place the crests of the
teeth as close to the scanner glass as possible, adjusting with the
magazines or thinner stackables. I work in a dark room, and cover the
whole opperation with a soft cloth to ellimenate extraneous light.  I crop
the scan to accommodate one group of teeth at a time then scan at a high
resolution, up to 1200 ppi (the smaller the specimen, the higher the ppi),
however, I find that 400 ppi provides enough detail for my purpose on
specimens over 5mm in length. I find that my scanner can pick up more
detail than I can see with a 10x handlens, but less than a dissecting
scope.  I use the scans as a reference, so overwhelming detail via higher
ppi is usually not necessary.

Details greater than 1cm from the glass tend to be obscured, and dramatic
perspectives occur beyond this distance- unless you seek to replace
accuracy with bizarre composition, I recommend using this technique on
objects under 3/4" thick.  I have had some success scanning my own hand as
a reference for surgical illustration, but had to subdue the extreme
perspective before my final transfer (emphasis on the word "reference".)

Photoshop from start to finish:
I typically send a print of these photo-like scans to the author
to ensure that I have the exact view (you can fax images straight out of
photoshop with the right software.) Once verified, I isolate the tooth
from the matrix with a path, feather the path to prevent hard edges, and
paint the tooth on a new layer over the scan.  I paint with the airbrush
and draw with the pencil in a stylized manner to describe the
mountainesque elevation changes.I always cover the scan completely with
hand shading, but retain it underneath as a reference should the author
have any questions about the anatomy.

Last tip:
I don't have access to a dissecting scope, but I find that I can use my
scanner's highest settings, then play with the image levels (contrast,
sharpness, etc.) to visualize another 10x worth of details that I can't
pick up with my hand lens. I use an Epson Expression 636.

If you do this type of work extensively, you'll save a great deal of time
by scanning and adjusting large batches of specimens.

Graham Johnson
Medical Illustrator
Baltimore, MD