Patent ID: 6176427
Filing Date: 2001-01-23
Classification: G06K

Abstract:
A method of decoding digital data values formatted into a pattern comprising the steps of:determining the locations of cells in a first grouping of contiguous cells where the grouping of contiguous cells contains digital data indicating information concerning the formatting of a plurality of the remaining cells in said pattern,deriving from said first grouping of contiguous cells said information concerning the formatting of a pattern of a plurality of the remaining cells in said pattern, where the deriving comprises extracting digital data from each cell wherein each cell contains at least one bit of data where one logical state is expressed by the presence in the cell of a spot with one set of attributes and at least one other logical state is expressed by the absence from the cell of a spot with the same set of attributes as a spot the presence of which expresses the first logical state,determining the locations of said plurality of the remaining cells in said pattern, where said step of determining locations is performed by reference to and use of at least some of said information concerning the formatting of a plurality of the remaining cells in said pattern,deriving digital data values from said plurality of the remaining cells in said pattern where the deriving comprises extracting digital data from each cell wherein each cell contains at least one bit of data where one logical state is expressed by the presence of a spot with one set of attributes and at least one other logical state is expressed by the absence from the cell of a spot with the same set of attributes as a spot the presence of which expresses the first logical state, whereby digital data is recovered from said pattern.