[sane-devel] Standard option definitions

Dave Close dclose@anim.dreamworks.com
Mon, 25 Mar 2002 10:06:12 -0800


Again, I never saw this on the list, only in a personal copy to me.
Unfortunately, I tend to ignore off-list replies to list posts.

Oliver Rauch wrote:
>what you are talking about are "well known options" like defined in the
>sane standard. For the SANE_DESC_SCAN_MODE you are right, this should be
>a well known option. The other listed options are hardware dependant
>options which are implemented different for all scanners, so it
>does not make sense to make this to "well known options".

I had mentioned SANE_DESC_SCAN_SPEED, SANE_DESC_CAL_LAMP_DEN,
SANE_DESC_SCAN_LAMP_DEN, and  SANE_DESC_SELECT_LAMP_DENSITY. All of
these are listed in saneopts.h. If they are hardware-dependent, they
should not appear there, but should appear only in the header file
associated with the specific backend.

Note that nearly all options are implemented differently for different
scanners. The fact that the implementation varies is no reason for an
option not to be standard, or "well known". My assertion is that any
option which appears in saneopts.h should be considered well known and
its usage should be well defined.

I also don't see why scanning speed should be less standardized than
brightness or contrast (for example), or specifically for the scanning
mode (gray, mono, lineart, etc). Many backends use the speed option,
presumably because they find it useful. However, there is no common
definition for the type of values associated (string or numeric) or
for the option values.

Can anyone answer my specific question about the LAMP options: should I
understand that "density" is, in some sense, equivalent to "intensity"?

>In general the frontend does not need to know about the options.

That may be true in the general case. I prefaced my post by noting that
"our practice is to provide a standard user interface for all of our
scanners." In a production environment, with technicians working on
several scanners and work generated by departments which never see the
scanners, a standard interface helps a great deal. We may be unique but
I suspect there are other production situations among SANE users. SANE
is not defined, so far as I know, as a hobbiest protocol only.

Dave Close                    Dreamworks SKG, Animation Technology
+1 818 695 6962               Glendale California 91201-3007
dclose@anim.dreamworks.com    http://www.dreamworks.com/