Casio IT-800 Series, Руководство пользователя программного обеспечения, Страница: 64 / 325

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Dual Decoder System
The dual decoder system initially decodes a scanned bar code data using the standard decoder, but
if decoding fails, it uses the following additional decoder to scan the same bar code. This dual
decoder system supports the bar code symbologies listed below.
- Code39
- Code128
- EAN
With the decoding system used for the previous Casio handheld terminals, decoding is processed
with a mean value of one module adding bar thickness of each black bar and white bar for one
character when performing binaryzation or quardruplzation of bar thickness. However, this
method does not accurately decode a bar code if it is formed with unbalanced bar thickness
between white bars and black bars.
The dual decoder system can solve it by calculating separately each mean value of black bars and
white bars for such a bar code with unbalanced thickness of white and black bars by changing the
threshold level of decoding.
The functions of the Laser Scanner Library relevant to the Dual Decoder System are as follows.
OBRSetDecodeLevel
:
Sets up decoding level.
OBRGetDecodeLevel
:
Retrieves decoding level.
Customizing the Decoder
According to the scan environment and the bar code printed material’s quality, the decoder can be
customized to efficiently improve scanning performance. First, to maintain scanning performance
with the normal decoding logic, perform decoding using with the decoder and if it does not
succeed the decoding, customize it so that the decoding can be performed for a better scanning
performance.
Table 2.51 Customizing the elements
Element Description
Change margin of the right
and left threshold values Used to change the threshold values of right and left side
marginal spaces which are allocated for areas colored in white
on the left and right sides of a bar code.
Change of compensation
values of the thickness and
thinness of a bar. Used to thicken or thin each bar of bar code for a specified value
and then decode it. Value for thickening or thinning each bar
can be changed.