scanning images and making thumbnails

[JQ Johnson]

robinsol at oclc.org (Robinson,Linda) writes:

>I'm a novice at images. I'm trying to  find out what resolution is best to
>scan photos and what software would help me make thumbnails or smaller
>copies of the scanned photos. I hope these aren't stupid, ignorant
>questions, but I'm ignorant in this area.  TIA
>Linda Robinson

It depends heavily on what you plan to do with the images, and to some
extent on how the photos were printed.  If all you want to do is publish on
the web, and you know what size (in pixels) you want your final product,
then scanning at that bit depth and resolution (often that translates to
scanning an original at 70 to 100dpi in 8 bit color) can be the best
approach.  On the other hand, you more typically want to do some image
manipulation, then scale the image for publication.  I find that scanning
photos at 300dpi in 24 bit color then reducing gives the best effects, and
gives high resolution "master" digital images that are suitable for
archiving.  300dpi and 8-bit grayscale is fine for most black and white
photos unless you want to capture that particular shade of sepia the photo
was printed in.  Even 300dpi is not enough for many archival needs, though.
If you want to capture the fine structure of a halftone print (let's say you
want to see the size of the screen, or even worse let's say that your
scanned photo has to be able to distinguish between the hard-edged dots of a
letterpress halftone print and the soft dots of a litho), you need to scan
at a much much higher resolution.

Any good image manipulation program can make thumbnails.  Photoshop is the
best, but the low cost programs like LView Pro, Paint Shop Pro, or
GraphicConverter (Mac) can do an acceptable job.  Hint:  apply a small Blur
filter (15%?) to the full-sized image before scaling it.  If you have a lot
of photos, a program that can do filters and scaling in batch mode is
essential.

JQ Johnson                      Office: 115F Knight Library
Academic Education Coordinator  E-mail: jqj at darkwing.uoregon.edu
1299 University of Oregon       voice: 1-541-346-1746
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