[sane-devel] Well known option consensus

m. allan noah kitno455 at gmail.com
Mon Jan 22 16:57:22 CET 2007

On 1/22/07, abel deuring <adeuring at gmx.net> wrote:
> m. allan noah wrote:
> >> > But back to the problem I have/had with Etienne's suggstion for the
> >> > "relations" between page size and scan window coordinates: It does
> >> > not make much sense to allow to set a scan window in overscan mode:
> >> > The backend should calculate the scan window settings automatically
> >> > from the page size, and disable the options tl-x, tl-y, br-x, br-y.
> >>
> >> No ! If a user want to scan only a portion of the paper, he must be able
> >> to set scan area, but as long as there is no scan surface, we use paper
> >> size as scan surface. That make sense !
> >
> > you missed the point here. we are talking about an overscan option, which
> > causes the scanner to add space all around the scan, such that the back-
> > ground shows thru.
> >
> > but i think a person might want to overscan and still have only a
> > small area of the page (one of the corners?) i think i can work this
> > out, and still be compatible with the text of our suggestion.
> Since the "level" of page size and skew detection is quite low in
> the scanners we're talking about, I think a backend does not need to
> do much here: In overscan mode, the backend simply returns the image
> of the document surrounded by "easily distinguishable", typically
> "dark" pixels; it is up to the frontend to detect the page borders
> and rotation angle.
> All this does not mean that the frontend cannot let the user select
> a smaller scan window within the page area -- but the clipping of
> the image must be done by the frontend.

i agree completely other than the last sentence. it should be possible
for the backend
to let the user select overscan mode, and then adjust the scan
area/papersize as needed
to set tl-x/y 0,0 to the black area 16mm outside of the paper. i dont
think this violates the
spirit of the standard proposal, and it keeps overscan mode as similar
to the other modes
as possible. in fact, i think this is the right thing to do in sane1,
given recent user complaints on this mailing list.


"The truth is an offense, but not a sin"

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