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Abstract

Prior methods of reading MaxiCode dataforms have been subject to reduced resolution image scaling and processing and speed constraints of Fourier transform computations. Described spatial domain data extraction methods provide bull's eye center location by T-sequence pixel pattern analysis, axis identification by moment analysis of data cell pairs, and integral width square wave analysis of illumination transitions to avoid reading-line cell fragmentation. The center and top of a MaxiCode are identified in high-resolution pixel data, without scaling reduction or Fourier type frequency domain processing. Data is extracted serially from rows of data cells by sampling along lines of pixels aligned by fragmentation analysis so as to traverse complete rows of data cells. Dynamic thresholding accurately defines illumination value transitions between adjacent linear groups of data cells, each group consisting of one or more data cells of the same reflectivity. Application of disclosed methods to other types of dataforms is described.

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First Claim