Bar-code reader, method of reading a bar code and computer product

A method of reading a bar code comprising:

• optically scanning a bar code to obtain optical power of light reflected from white bars and black bars of the bar code;
• calculating a differential of the optical power to obtain a differential waveform;
• dividing the differential waveform into a positive waveform and a negative waveform;
• calculating correct widths of black bars in the bar code from the positive waveform and the negative waveform and creating corrected bar-code data;
• and
• converting the corrected bar-code data into character data that is an array of numerals and alphabets.

A computer program that makes a computer execute:

• optically scanning a bar code to obtain optical power of light reflected from white and black bars of the bar code;
• calculating a differential of the optical power to obtain a differential waveform;
• dividing the differential waveform into a positive waveform and a negative waveform;
• calculating correct widths of black bars in the bar code from the positive waveform and the negative waveform and creating corrected bar-code data;
• and
• converting the corrected bar-code data into character data that is an array of numerals and alphabets.