digital images of type specimens

Doug Yanega dyanega at DENR1.IGIS.UIUC.EDU
Tue Aug 22 11:01:52 CDT 1995

Shawn Landry asks:
>I am looking into the various techniques to take digital images of type
>specimens and would like to speak with anyone else involved with the
>issue.  I am in need of specific product info as well as information
>regarding the best (or most appropriate) techniques.  Specifically, I
>would like to hear from people who have compared the use of a digital
>camera with that of a video camera and video capture technique and/or
>scanning of 35mm slides.

For a Cerambycid field guide I've written, we've had 400 35mm slides
scanned and digitized, and I think the result (and conclusion) is not too
surprising. The slides themselves have better resolution, of course, but
the scanning technology is such that the digital image, when *printed*, is
not noticeably different from having the plates made directly from the
slides (at least at the magnification we are using, where each slide's
worth of image is about 35mm on the final printed page). But, that's for a
*printed* version...
        I've also seen some video capture systems, and though I haven't
done direct side-by-side comparisons with our digitized slides, I wouldn't
say there was a noticeable difference in image quality - though logically,
the poorer the resolution of the slides, the better (relatively) the video
capture would become, since the video is of the specimen itself (where the
slide adds an extra step in which *some* detail is likely to be lost). I'm
not fluent in the fine points of the hardware, but the high-resolution
scanning option provides a LOT of lines per inch (or however one phrases
digital resolution), and probably not too different from the video system.
I'm sure that this is the crucial feature of concern to you, but I've been
led to understand (in the process of having my slides done) that not all
scanning systems and video systems offer the same digital resolution;
probably a matter of how much you're extra willing to pay for successive
small increments in quality. My gut feeling is that the video/digital
camera is likely to offer the better end product because it cuts out the
intermediate step. I don't know how digital camera images compare in lines
per inch to video capture, however. Maybe someone else can help you

Doug Yanega      Illinois Natural History Survey, 607 E. Peabody Dr.
Champaign, IL 61820 USA     phone (217) 244-6817, fax (217) 333-4949
  "There are some enterprises in which a careful disorderliness
        is the true method" - Herman Melville, Moby Dick, Chap. 82

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