If user has control over printing process, the following goals might be important:

• Target AvrModuleWidth to be larger than 3.
• Reduce file size of scanned images.  To do this scan at 200dpi, instead of 300 dpi.   If image is faxed, 192 dpi horizontal resolution is used by default.

Based on this we can calculate parameters of  barcode generation and printing stages.
Barcode size calculation:

• Let us assume input data is a string of 10 characters long, e.g. "0123456789" (C=10)
• Let us assume we will use Code 128.   According to standard number of modules in barcode including start/stop characters and checksum is: N= 11*C + 35 = 145 modules.
• To get AvrModuleWidth = 3 pixel after scanning size of barcode image in pixels should be: P= 145*3 = 435 pixels.
• If scanning at  200dpi, length of barcode on paper should be: L=435 / 200 = 2.175 in.
• Barcode generation software should be set to produce 2.175 in. barcode. See below.

During barcode printing it is important to accurately transfer the generated barcode symbol to paper.  The critical parameters are: module size and printing resolution.   To minimize printing digitizing error, the number of printed dots per module should  be an integer number.

• The Size of a module of printed barcode should be: 2.175 / 145 = 0.015in.  
• This corresponds to module density of 66.67 modules/inch.
• If printer resolution is 300 dpi, number of dots per modules:
  D = 300 / 66.67 = 4.5   Since this is NOT close to the whole number, printing digitizing error will be introduced. It would be a good idea to increase the size of the barcode by about 10% to 5 dots per module and 2.4 inches in overall size.
  
  Using 600dpi printer, the number of dots per module is:
  D = 600 / 66.67 = 9  Since this is a whole number, the printing will generate no digitizing errors.

Conclusions and alternatives:  

• To achieve a 100% recognition rate with this examle, the barcode should be printed on 600dpi printer and it should be 2.175 in in size.
• With 300 dpi scanner barcode size could be reduced even more, to 1.45 inches, and a 300 dpi printer would be OK. 
• If barcode image has no distortions (good brightness, no dirt, etc.) AvrModuleWidth = 2 should be sufficient  to achieve 100% recognition.  

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