Yes Lourens, I have already tried simple things like that.  Unfortunately
there is far too much variation within each individual image for that to be
successful.  Thanks for the suggestion though anyway.


----- Original Message -----
From: "Lourens Veen" <[EMAIL PROTECTED]>
To: "Kevin Myers" <[EMAIL PROTECTED]>; "gimp users"
Sent: Thursday, October 17, 2002 4:32 AM
Subject: Re: [Gimp-developer] Adaptive Thresholding Plug-In

On Thursday 17 October 2002 02:15, Kevin Myers wrote:
> Hello,
> Has anyone out there already written or come across a GIMP
> plug-in or script that is designed to do adaptive thresholding of
> an image?
> I have a large number of extremely large scanned grayscale images
> that need to be converted to black and white.  Problem is that
> the contrast and especially brightness of these images vary, not
> only between different images, but also over different areas of a
> single image.  It is NOT adequate to choose a single threshold
> value that will work across all of these images, or even across
> the entire portion of a single image.
> I've tried using the Adaptive Contrast plug-in as a preprocessor
> step to thresholding, but that plug-in doesn't seem to be giving
> me the appropriate level of contrast boost and brightness shift
> that would be needed.

Have you tried doing an Image->Colors->Auto->Stretch Contrast before
tresholding at a fixed value (say 128)? I'd say that that should
help a great deal.


PS: I think this one belongs in gimp-user, not gimp-devel. Please CC
me, I'm not on gimp-user.
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