"Invisible" <voi### [at] devnull> wrote in message 
news:4aeaea24@news.povray.org...
> I'm currently writing a small Haskell library for this. Currently it 
> understands 2 of 5 standard and interleaved, code 128, and I'm currently 
> implementing code 39. Of course, the library only handles converting 
> characters into 1s and 0s and back again. In "real" barcode handling 
> things are far more complex; bar thicknesses have to be within certain 
> tollerances when printing, and scanning is a fairly sophisticated 
> problem...

I've never tried to implement a scanning algorithm, but it looks like an 
interesting challenge. Not much novelty in it, I s'pose, although there 
might be some room to develop more sophisticated two dimensional bar code 
scanning processes.

When I had to make my own code 39, I coded for a specific model of laser 
printer at 300 dpi, and I translated the tolerances to integer values before 
I made my translation table, then translated those into the graphics command 
that drew filled rectangles on the printer. That restricted the size 
variations I could do, but it kept me from having slight variations in size 
due to rounding errors; mostly all that was so that I could get the software 
done and out the door quickly.

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