David Key, Irvine CA, the bar coding technology expert explains about the effects of Fax transmission on bar code decoding, he says as per the faxed documents of bar coding symbols, it has been ascertained that the quality of bar code symbols have been degraded. All the documents are scanned by the fax machines in accord to the standard resolution sampled as per 98 vertical dots per inch and 204 horizontal dots per inch.
Afterwards, each and every sample point is translated into a black or white value, a procedure known as binarization. According to this process, the straight lines of the bar code symbols are converted into ragged ones, altering the width of spaces and bars. Every additional fax cycle extends to delineate the quality of a bar code. In fact, at a certain point, the symbol is not able to get decoded by the bar code decoding software.
David Key, Irvine CA tells two symbologies in order to explain Effects of Fax Transmission:-
1. (1D) Linear symbologies – Two most popular linear symbologies were analyzed and tested – Code 39 and Code 128. Code 39 uses two bar and space widths to convert the information whereas Code 128 uses four. Afterwards, thirteen most belittled module sizes varying from 12.5 to 32.5 mil of every symbol form were encoded and printed on a sheet. The sheet was beamed and sent via fax at standard resolution for ten cycles. The resulting eleven pages were scanned via scanner at approx. 300 samples per inch and were represented to a bar code decode software. Both bar code symbologies were able to successfully decode for 3 faxes at 2.6 samples per module, whereas the same codes having 6.6 samples per module were able to read even after 10 faxes. There is one thing to consider i.e. the greater the size of the module of linear code is, the more horizontal it will be to encode the same amount of data, but the larger module sizes can improvise the read rate.
2. (2D) Matrix symbologies – This process renders better information about the accuracy and density as the information gets encoded in both vertical as well as horizontal directions. The data matrix used was a 12*12 module square symbol, and 2D symbols can be printed with much greater size module symbols, as compared to linear symbols encoding the same information.
In a nutshell, if the documents comprising varied bar code symbols are faxed multiple numbers of times, then the bar code symbols get printed with a greater sized module to be successfully decoded.
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David Key Irvine California 