Having done a fair amount of preparation of coin images (my wife is a
kinda high-volume eBay seller), let me recommend using a camera on a
copy stand instead of a scanner for acquiring the original image. To
start with, scanners generally have a light source co-located with the
imaging sensor, both orthogonal to the scanning surface. What this does
is pretty much kill shadowing which pretty much kills any sense of depth
on the surface of the coin, and it can result in glare. Further,
scanners have close to zero depth-of-field. With a camera, you can
control the lighting, control depth-of-field, use polarising filters to
kill glare, and so on.
And /then/ use gimp for post-process!
And +1 on Vuescan.
Chris Moller
On 01/17/16 12:10, Jay Smith wrote:
On 01/13/2016 12:11 PM, billgoldbeach@xxxxxxxxxxxx wrote:
Greetings, I have heard Gimp is great for scanning images of
coins to be sold internet. Can you tell me to set up Gimp to do
this?Regard,William.
Sent from my Verizon 4G LTE Tablet
Disclaimer: I am a stamp guy, not a coin guy, but we do use Gimp. I do
not have any coin scanning experience.
As others have said, Gimp does not scan by itself. And even if you
have the TWAIN plug-in built, that is still not the "secret sauce".
Once you have the scan made, Gimp may have features that are (or are
not) easier to use than some other programs for manipulating the
images to make the coins look their best. You really have to have an
in-depth conversation with those from whom you "heard" that Gimp is
great for coins. If they are able/willing to tell you their "secret
sauce", the workflow may be technical and a bit complicated, but take
good notes. Included in these notes must be the make/model of the
specific scanner(s) people are using. Since coins are three
dimensional, it all becomes about the light source and mechanical
operation -- and that can vary greatly from one scanner model to
another. I would not be surprised to discover that it is a specific
make/model of scanner that is really the "secret sauce".
However, IMHO what you need -- regardless of whether you use Gimp or
not -- is a standalone scanning program (usually _not_ from the
scanner's manufacturer -- those tend to be much too dumbed-down). From
my professional (again, in stamps) experience, I recommend Vuescan
Professional (VSP). A free/lite version can be downloaded from
http://www.hamrick.com but if you find that works for you, then I
_strongly_ recommend paying the FEW dollars for the full Professional
version. By the way, this is a family operated company and when I
have run into tricky issues (because of my stamps, not their
software), Mr. Ed Hamrick himself has been quick to assist with ideas.
VSP supports "over 2800" of makes/models of scanners, including
scanners not supported by your operating system! They have Windows,
Mac and Linux versions.
VSP can also build and load a "profile" (think color calibration) of
your scanner. https://www.hamrick.com/vuescan/html/vuesc17.htm
You will probably need to obtain a "color target card" separately(see
that link for the source where I got mine; it is in Germany; I did not
find an American source). VSP can make and load scanner profile files
that you can create using VSP (specifically/separately for each
scanner machine you use). This profile allows you to have much better
understanding and control of the color range (sorry, I am not
technically qualified on this subject) that the scanner machine is
sending to the VSP software and it allows VSP to more closely turn
that into what you really want to see. In this way, using multiple
scanners -- which can have slightly different output even if the same
make/model -- you can have virtually identical color output (and
control of same).
Best of luck,
Jay
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