Machine-readable symbols

A method of decoding a machine-readable symbol configured as a set of marks formed in a surface of an object, a presence or absence of a mark in each cell of an array of cells designating a binary state of the each cell, the method comprising:

• acquiring an image of the machine-readable symbol;
• identifying the cells of the array from the acquired image;
• evaluating reference cells of the array in accordance with a reference standard for the machine-readable symbol to identify optical characteristics consistent with the presence or absence of a mark in the reference cells;
• classifying nonreference cells of the array in accordance with the identified optical characteristics to determine the presence or absence of a mark in the nonreference cells;
• compiling classifications of the nonreference cells into a binary grid;
• and
• decoding the binary grid.

A system for decoding a machine-readable symbol configured as a set of marks formed in a surface of an object, a presence or absence of a mark in each cell of an array of cells designating a binary state of the each cell, the system comprising:

• an illumination source disposed to illuminate the machine-readable symbol;
• an imager disposed to acquire an image of the illuminated machine-readable symbol;
• and
• a computational unit interfaced with the imager, the computational unit having:
• instructions to identify the cells of the array from the acquired image;
• instructions to evaluate reference cells of the array in accordance with a reference standard for the machine-readable symbol to identify optical characteristics consistent with the presence or absence of a mark in the reference cells;
• instructions to classify nonreference cells of the array in accordance with the identified optical characteristics to determine the presence or absence of a mark in the nonreference cells;
• instructions to compile classifications of the nonreference cells into a binary grid;
• and
• instructions to decode the binary grid.