Method of decoding a pattern-encoded coordinate
AssigneeSilverbrook Research Pty Ltd
InventorsPaul Lapstun, Jonathon Leigh Napper
Life of this patent
Estimating the term…
Abstract
A method of decoding a coding pattern disposed on or in a substrate. The method comprises the steps of: (a) operatively positioning an optical reader relative to a surface of the substrate; (b) capturing an image of a portion of the coding pattern, the coding pattern comprising a plurality of square tags of length/identifying two-dimensional location coordinates; and (c) sampling and decoding x-coordinate data symbols within the imaged portion and y-coordinate data symbols within the imaged portion. The imaged portion has a predetermined diameter and is guaranteed to contain sufficient data symbols from each of the Reed-Solomon codes so that symbol errors are correctable in each of the codes during the decoding.
Claims20
A method of decoding a coding pattern disposed on or in a substrate, said method comprising the steps of:
- (a) operatively positioning an optical reader relative to a surface of said substrate;
- (b) capturing an image of a portion of said coding pattern, said coding pattern comprising a plurality of square tags of length l identifying two-dimensional location coordinates, each tag comprising:
- a plurality n1 of x-coordinate data symbols encoding a respective (n2, k) Reed-Solomon code for an x-coordinate;
- a plurality n1 of y-coordinate data symbols encoding a respective (n2, k) Reed-Solomon code for a y-coordinate;
- a number z of said x-coordinate data symbols positioned in a central column of width q in each tag with a remaining (n1−z) x-coordinate data symbols distributed evenly on either side of said central column;
- and
- a number z of said y-coordinate data symbols positioned in a central row of said tag of width q with a remaining (n1−z) y-coordinate data symbols distributed evenly above and below said central row, wherein n1≧n2 and z≦1;
- (c) sampling and decoding at least one of:
- x-coordinate data symbols within said imaged portion;
- and
- y-coordinate data symbols within said imaged portion,
- wherein said imaged portion has a diameter of at least (l+q)√2 and less than (2l)√2 and is guaranteed to contain at least (n1+z)/2 data symbols from each of said Reed-Solomon codes, and wherein one or more symbol errors are correctable in each of said codes during said decoding.
A system which decodes a coding pattern, said system comprising:
- (A) a substrate having a coding pattern disposed thereon or therein, said coding pattern comprising a plurality of square tags of length l identifying two-dimensional location coordinates, each tag comprising:
- a plurality n1 of x-coordinate data symbols encoding a respective (n2, k) Reed-Solomon code for an x-coordinate;
- a plurality n1 of y-coordinate data symbols encoding a respective (n2, k) Reed-Solomon code for a y-coordinate;
- a number z of said x-coordinate data symbols positioned in a central column of width q in each tag with a remaining (n1−z) x-coordinate data symbols distributed evenly on either side of said central column;
- and
- a number z of said y-coordinate data symbols positioned in a central row of said tag of width q with a remaining (n1−z) y-coordinate data symbols distributed evenly above and below said central row, wherein n1≧n2 and z≧k;
- and
- (B) an optical reader comprising:
- an image sensor which captures an image of a portion of said coding pattern, said image sensor having a field of view with a diameter of at least (l+q)√2 and less than (2l)√2;
- and
- a processor configured to the steps of:
- (i) sampling at least (n1+z)/2 data symbols from at least one of said Reed-Solomon codes;
- and
- (ii) decoding at least one of:
- said x-coordinate data symbols within said imaged portion;
- and said y-coordinate data symbols within said imaged portion,
- wherein said processor is configured to correct one or more symbol errors in each of said codes when decoding said x-coordinate and y-coordinate data symbols.
An optical reader which decodes a coding pattern disposed on or in a substrate, said coding pattern comprising a plurality of square tags of length l identifying two-dimensional location coordinates, each tag comprising:
- a plurality n1 of x-coordinate data symbols encoding a respective (n2, k) Reed-Solomon code for an x-coordinate;
- a plurality n1 of y-coordinate data symbols encoding a respective (n2, k) Reed-Solomon code for a y-coordinate;
- a number z of said x-coordinate data symbols positioned in a central column of width q in each tag with a remaining (n1−z) x-coordinate data symbols distributed evenly on either side of said central column;
- and
- a number z of said y-coordinate data symbols positioned in a central row of said tag of width q with a remaining (n1−z) y-coordinate data symbols distributed evenly above and below said central row, wherein n1≧n2 and z≧k;
- said optical reader comprising:
- an image sensor which captures an image of a portion of said coding pattern, said image sensor having a field of view with a diameter of at least (l+q)√2 and less than (2l)√2;
- and
- a processor configured to perform the steps of:
- (i) sampling at least (n1+z)/2 data symbols from at least one of said Reed-Solomon codes;
- and
- (ii) decoding at least one of:
- said x-coordinate data symbols within said imaged portion;
- and said y-coordinate data symbols within said imaged portion,
- wherein said processor is configured to correct one or more symbol errors in each of said codes when decoding said x-coordinate and y-coordinate data symbols.
Dependencies are inferred from the claim text.