On 06/13/2009 02:46 PM, Chris Mohler wrote:
> On Sat, Jun 13, 2009 at 1:08 PM, Jay Smith<j...@jaysmith.com> wrote:
> [big snip]
>> So....
>> I am hoping for suggestions as to a) how to avoid the color shadow of
>> using a colored background and b) if it cannot be avoided, how to fix it
>> in gimp without a lot of messing around and/or other color distortion
>> problems.
> Have you tried putting something heavy on the "colored background" (I
> tend to use a thick book)?  This may reduce or eliminate the shadow.
> Have you tried reducing the wand (or select by color) tool's threshold
> when selecting the black background?  I would guess that the postmark
> color and the background color differ at least slightly.
> A couple of the raw scans of the stamps might be useful for analysis.
> Chris

Yes, we have weighted the item on the scanning bed.

The scanner is able to pick up the thickness of the postage stamp paper
(the shadow caused thereby) because from either the leading or trailing
direction, the light source causes a very slight shadow that the scanner

And, yes, we have played extensively with the selection tool's
threshold.  Doing so solves problems in some spots, but creates problems
in others.  The shades of black are quite variable.


Using a "blue screen" method in which I would use a background of some
outrageous color that is not present anywhere in the items to be
scanned, what would the best tool/method to use to select and eliminate
ALL of that color?  Again, the problem is that the background itself can
be removed, but at the above described "shadow edge", there is a
gradation of color.  Of course the catch is that there is no background
color will work all the time.  I can't simply delete all reds or all
blues or all ...whatever.


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