[Printers] More thoughts on Toshiba/Kyocera/HP code

[Patrick Burns]

Hi again.

Umm, hang on. Does anyone see an interesting code here? OK, you've
divided each data row into an A side and a B side. And in each side of
each row there are 8 bits. And you've coloured them in in groups of two
(two light, two dark, two light, two dark.)

Let's divide each pair into a "left" and a "right" bit. So a single row
would look like this:

 A-side   B-side
LRLRLRLR-LRLRLRLR
LRLRLRLR-LRLRLRLR etc.

In every row of every bit pattern, when there is a bit in an "L"
position on the A-side of a row, the corresponding B-side bit is also in
an L position. If a bit on the A-side of a row is in an "R" position,
the corresponding bit on the right side will be in an "R" position.

Furthermore, there are two L-bits and two R-bits in each of the eight
groups.

And further, each row alternates L,R,L,R or R,L,R,L.

And further, all the "parity" bits for a block are either all "L" or all
"R".

I was wondering why the pattern looked so cool :-). The dots are placed
to make the pattern have these properties. This makes the code quite
robust against errors, as you can check every block fulfills these
properties.

Perhaps the information is encoded by re-arranging the locations of the
dots to have certain properties. I.e. the bits themselves don't mean
anything, but the way sets of bits are arranged spells out some code.

Obviously if the code has to satisfy all these properties, the capacity
of the code is further limited. How many unique combinations could be
encoded this way?

Is this just a stupid observation, or could it mean something?

-- 
  Patrick Burns
  pb at fusion.fastmail.fm