[GRLUG] LINUX and NOT LINUX

[Bob Kline]

On Tue, Sep 15, 2009 at 1:28 PM, Michael Mol <mikemol at gmail.com> wrote:

> On Tue, Sep 15, 2009 at 1:13 PM, Bob Kline <bob.kline at gmail.com> wrote:
> > On Tue, Sep 15, 2009 at 12:56 PM, Michael Mol <mikemol at gmail.com> wrote:
> >> On Mon, Sep 14, 2009 at 5:18 PM, Bob Kline <bob.kline at gmail.com> wrote:
> >> > In the LINUX column, I discovered that
> >> > LINUX does not support Canon scanners.
> >> > I tried XSane and Scanlite.  XSane will
> >> > produce a scan, but the colors are way
> >> > off, and I couldn't find a way to correct
> >> > them.
> >>
> >> Have you tried building a color profile for the scanner?  The lprof
> >> package looks like it might help.
> >>
> > That's the kind of thing Canon and
> > others provide you when they supply
> > you with a CD for your windoz system.
>
> *Sometimes* they do, and it depends on the device.  However, each
> device will have slight difference resulting from the manufacture
> process, and it's not unknown for professionals who want the greatest
> precision and accuracy to build their own color profiles.
>
> In the case of monitors, the color profile is often generated
> afterward by software you install on your system.
>
> [snip]
>
> > See: http://en.wikipedia.org/wiki/Linux_color_management
> >
> > and in particular:
> >
> > Software for input and output profiling
>
> See "apt-cache search ICC|less".
>
>
> > Looks to me like this is a big enough job
> > that it should only be done once, preferably
> > by the people doing the reverse engineering.
>
> No, because there are manufacturing level differences that are
> important if you want precision.
>

I suspect for most people those
differences are quite minimal.  i.e.,
the sensors are solid state, and
probably pretty uniform to start with.

That said, the little package for windoz
that comes with the unit does have a
calibration step when you turn on the printer.
It uses the white surface of the cover, which might
be where the uniformity you refer to
really comes in. ( For this reason one
doesn't want any material in the scanner
when they start..... )

I just looked at my HP unit, and there
too, the white cover could be used.  If
one knew how that calibration program
works, it would be nice to have under
Linux.  That way one only has to assume
they know the white cover material is
in place.

>
> > It take equipment the typical putterer is not
> > likely to even have access to, much less own.
>
> Reverse-engineering USB traffic between Windows and a USB device?
> Windows VM guest on a Linux host, using the tools that exist on Linux
> for sniffing USB traffic.  No special hardware required.
>
> No, the photometric equipment and
charts referred to.  Less of on issue on
output,  you nevertheless need to have
some concept of when you've arrived.
Maybe color charts.  Things like color
accuracy span the gamut from your
device to room light to whether you're
color blind in any way.  Real precision
is an art.  Go to a paint store for a color
today and they just might have you
stand in a booth where you first adjust
the lighting, to give you some idea what
will happen after you buy it and splatter
it on your walls.

Anyway, this is all good stuff to know
about.  Even though my Canon FB630Ui
is ten years old now, and likely long out
of production, I will at least interact with
the people doing the real work and see if
they're interested in tuning up support
for it.

    -- Bob
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