Inconspicuous optical tags and methods therefor

An optical tag having an inconspicuous machine-readable bar code pattern, comprising:

• a patterned layer having distinguishable first and second portions that define the bar code pattern, the first portions selectively filtering a first spectral portion of light from other light wavelengths;
• an indicia layer disposed to overlap the bar code pattern so as to mark a location of the bar code pattern;
• and
• a contrast enhancing layer disposed behind the patterned layer and configured to enhance a contrast of the bar code pattern.

A method of reading an optical tag having an inconspicuous pattern, the method comprising:

• illuminating the tag;
• imaging the illuminated tag to provide a full-color image, the full-color image having red, green, and blue color components;
• and
• isolating the blue color components to provide a monochrome image from the full-color image, the monochrome image providing enhanced detection of the pattern relative to the full-color image.

A method of reading an optical tag having an inconspicuous pattern, the method comprising:

• illuminating the tag;
• imaging the illuminated tag to provide a full-color image, the full-color image having first, second, and third color components;
• and
• isolating the first color components to provide a monochrome image from the full-color image, the monochrome image providing enhanced detection of the pattern relative to the full-color image.