[gscan2pdf-help] Documentation of the numerous controls?

[Alan D. <ala...@gm...>]

Maybe when I have some time, I could take a stab at putting together a
guide to some controls of Gscan2pdf. But first, I would need to understand
them.  I have been operating on a hit and miss basis with especially the
controls in the "clean up: menu.  I am starting to understand a little
about some of the controls, but, really, I don't have a firm understanding
either of what such controls as "deskew" (or NOT), as opposed to "border
scan" or "border align".  And what do the filter parameters mean?  ""White
Threshold" or  "Black Threshold"?  What would be some approximate values
that might alter the way the cleanup works?

An example about the last.  I was able to obtain an aging document that had
been scanned on a good book scanner by a library, that had three layers.
It was tedious to skip two layers (each page represented on three pages, a
background maybe, a blurry filter layer, and an image layer) for each
page.  I have tried running unpaper (clean up) on such documents, sometimes
hundreds of pages long.  Even on a single page, one might get a part of the
page that goes completely white, a part (hopefully the text) that is
perhaps black or gray, and a, literally, "gray area" that I just cannot
seem to make turn white with any alteration of widgets.  Often these are
edges of pages, or parts of stiffly bound books that will not lay flat and
take on a gray cast.

Anyway, this is only one example.  There are others that are completely
cryptic to me: noise filter, blur filter, gray filter, mask centering, "no
mask scan".  Why 0.90 is the default for the white filter, and 0.33 for the
black?  It would be great if there were a "reset to defaults" button on
this page of filters, to get back to some known status, after trying
desperately to tweak these, to me, cryptic values.

I understand that my use case is outside parameters of normal use, when I
open a large PDF and try to clean it up.  it does sometimes work, and it's
a blessing when it does, an example of the true value of Free Software, for
which I thank you.  Amazing work.

I am happy to report that I am able to get a somewhat coherent pure text
copy of a file out of an OCRed document.  When I need this, it is fantastic
to have.

I never have figured out how to get back to the main window after calling
gimp on a page.  Gimp has been useful.  If one could select a page range
and automatically move to the next page?  Maybe this is already possible.
Should one save the file, kill gimp, or what?

I don't have a mail server on my machine, and I eschew Thunderbird.  So
when I try to send a scan by email, it leads to frustration.  Not a big
deal, because anymore, I just ignore this button.

Saving as a pdf winds up with a peculiar default for the filename.  A query
would help me.  It was never clear from the layout of the "save" screen
what the file name might end up being.

I am forgetful enough that I get stuck farily often on a long process that
is going through "all" pages, and don't know how to override it.  By the
opposite token, I often find that a file I have saved was a single page pdf
from a long series.  The latter can be and has been catastrophic.  The
first is truly annoying.  Perhaps the preferences menu would have helped me
with these things, but I am one of those people who don't take long time
outs to read EULAs, or, in this case, the documentation that I am
complaining to much about.  (Actually, I do see that I can set some
defaults for file names for PDFs. )

Reading through the documentation, I wonder "what is a Gaussian operator of
the given radius and standard deviation"?   Gimp does this too.  Fiddling
sometimes works.

I love Gscan2pdf.  It's my goto scanning application.  By the way, I think
to answer all of these questions in a single or small number of responses
is unreasonable to expect.  Once I got rolling, the ideas started flowing.

Thank you for this awesome program.

Alan Davis

-- 
 “The Universe is under no obligation to make sense to you.”
             --- Neil deGrasse Tyson

 *"I've never let my school interfere with my education."*
            ---- Mark Twain