Re: Compression, encoding, entropy

From: Edward Cherlin <edward_dot_cherlin_at_etssg_dot_com>
Date: Fri May 07 2004 - 14:08:21 CDT

On Sunday 02 May 2004 12:44, Alan Dechert wrote:
> Charlie,
>
> > Alan I agree. If the information can be fit into a simple
> > linear barcode it makes sense to keep it simple. I think a
> > lot fo the discussion got off track resolving the
> > distinction between not-wasting bits (optimal encoding) and
> > compression (changing the average run-length).
>
> Right. And while we're at it, we need to add printing to the
> list of research questions. The testing we've done so far
> tends to indicate minimal requirements for the printer when
> using 1-d Code128 barcodes. Although I tend to think inkjet
> printers may not be the best way to go (lasers are much faster
> and toner cartridges are better than inkjet), I was able to
> print perfectly readable barcodes on my 6-year old HP Deskjet.
> The 1-d barcodes came out fine on 300, 600, and 1200 DPI
> laser printers. We have not done any testing printing 2-d
> barcodes so we just don't know enough. It seems likely 2-d
> barcodes will have more demanding requirements for the
> printers. So it might be that both the printers and the
> readers will be more expensive. We just don't have enough
> information to make an informed decision on this right now.
>
> Alan D.

These questions are not difficult to answer. A little Googling
brought me to

http://www.mecsw.com/specs/datamatx.html
DataMatrix is a two-dimensional barcode which can store from 1 to
about 2,000 characters. The symbol is square and can range from
0.001 inch per side up to 14 inches per side. As an example of
density, 500 numeric only characters can be encoded in a 1-inch
square using a 24-pin dot matrix printer.

So that's 500 4-bit numeral codes, or 2,000 bits, readably
printed at pitiful resolution in one square inch, less space
than our 1D barcode. Any ink-jet or laser printer can do much
better.

-- 
Edward Cherlin, Simputer Evangelist
Encore Technologies (S) Pte. Ltd.
New voices in the global conversation
http://www.ryze.com/go/Cherlin
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Received on Mon May 31 23:17:23 2004

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