Re: How dark is a mark?

From: Rick Carback <carback1_at_umbc_dot_edu>
Date: Wed Dec 19 2007 - 11:17:35 CST

Perhaps I have misheard, but isn't one of the ideas behind the scanner
supposed to be that it present a screen showing what the scanner read on the
ballot?

If that's the case, you could do some interesting post-processing.
Minimizing or eliminating the need for calibration might be worthwhile...For
instance, it could take the "darkest" marks as the right marks. It could
also do edge-detection and corrective rotation of the scanned image.

-R

On Dec 19, 2007 11:51 AM, Douglas W. Jones <jones@cs.uiowa.edu> wrote:

>
> On Dec 19, 2007, at 10:10 AM, Richard C. Johnson wrote:
>
> > Doug Jones cited "competently made erasure" as a standard for
> > ballot scanners. I would respectfully disagree. Erasure is far
> > too variable; I would encourage voters who make an error to return
> > a spoiled ballot for a fresh one and vote their intentions.
>
> Absolutely! There is a big difference between what we recommend
> to voters and how we test the calibration of scanners. We recommend
> that voters not erase, we recommend that they spoil the ballot and
> get a new one (at polling places) or force an overvote with a big
> X to cross out the bad choice and properly vote their intention
> (so that the canvassing board can resolve the correction) on an
> absentee ballot.
>
> But, when calibrating the scanner, it is a good idea to calibrate it
> so it ignores well-made erasures and hesitation marks, while sensing
> that single stroke through the voting target using the recommended
> marking device.
>
> > Erasure is never a good idea with scanners, and I would not allow
> > erasers in a polling place.
>
> You cannot prevent a voter from making an erasure. You cannot prevent
> a voter from using whatever pen or pencil is handy. The most you can
> do is recommend and encourage.
>
> > The most egregious provision would have voters erasing in the
> > case of over votes rather than turning in the spoiled ballot for a
> > new one.
>
> We did this in Johnson County Iowa for several years. Each polling
> place was equipped with a new gum eraser. Voters voted with number 2
> hard lead pencils on ballots scanned by Optech I and II scanners (they
> are the same machine). The scanners were configured to kick back
> overvotes. If the voter's erasure worked, the scanner would accept
> the ballot. If not, it would kick back again and the voter was given
> a replacement. There was no override provision on this scanner, it
> was either kick back all overvotes or silently accept all.
>
> Hava sent those scanners to wherever old equipment goes after it's
> illegal to use in polling places. Probably some sweatshop
> disassembly line in China.
>
> > Hesitation marks, as opposed to a stroke of the pen or pencil, can
> > readily be ignored by scanners.
>
> Not so easily. The Optech 4C was developed to scan pencil, and then
> they re-tuned it to scan ballpoint pen in Phoenix. They ran the
> sensitivity up to the point where it could almost reliably sense a
> single stroke of a ballpoint, and at that point, any faint pencil mark
> or complete erasure was sensed as a vote. Subliminal marks were
> sensed.
>
> Bic black ballpoint ink is not very black when illuminated with a
> red LED (the Optech 4C does not use infrared to scan voting targets,
> but it does use infrared to scan the index marks, according to the
> patent).
>
> > Otherwise, it would be nightmare for voting officials to have to
> > evaluate one erasure against another, especially where an erasure
> > is attempted on a full marked ballot choice.
>
> The scanner's ability to ignore erasures and smudges is a matter of
> making a good faith effort. Beyond that, the instructions should seek
> to minimize the frequency of these efforts.
>
> Technically, distinguishing between erasures and deliberate marks is
> a matter of looking at the derivitive of the intensity signal. You
> are looking for edges. Deliberate marks have sharp edges, while
> erasures and smudges do not. Some discrete sensor scanners had a
> degree of edge sensitivity to help them ignore smudges. To my best
> knowledge, the current crop of pixelizing scanners (dating back to
> 1995) are all based on simple intensity measures over the sensing
> area. This will change.
>
> Doug Jones
> jones@cs.uiowa.edu
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Received on Mon Dec 31 23:17:06 2007

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