Abstract: This invention provides self-clocking glyph shape codes for encoding digital data in the shapes of glyphs that are suitable for printing on hardcopy recording media. Advantageously, the glyphs are selected so that they tend not to degrade into each other when they are degraded and/or distorted as a result, for example, of being photocopied, transmitted via facsimile, and/or scanned-in to an electronic document processing system. Moreover, for at least some applications, the glyphs desirably are composed of printed pixel patterns containing nearly the same number of ON pixels and nearly the same number of OFF pixels, such that the code that is rendered by printing such glyphs on substantially uniformly spaced centers appears to have a generally uniform texture. In the case of codes printed at higher spatial densities, this texture is likely to be perceived as a generally uniform gray tone.

Abstract: An optical image bar utilizing polarized light and a coherent spatial light modulator, includes birefrigent spatial or angular shearing means for uniformly dividing the spatially modulated radiation of a coherent image bar into a pair of laterally offset, redundantly modulated, orthogonally polarized optical field distributions. Imaging optics, which include any spatial filtering and/or polarization filtering elements needed for converting those field distributions into correspondingly modulated spatial intensity distributions, bring the filtered field distributions to focus on an output image plane, thereby producing redundantly modulated, laterally offset, intensity profiles on the output image plane which spatially sum with each other on an intensity basis.

Abstract: This invention provides self-clocking glyph shape codes for encoding digital data in the shapes of glyphs that are suitable for printing on hardcopy recording media. Advantageously, the glyphs are selected so that they tend not to degrade into each other when they are degraded and/or distorted as a result, for example, of being photocopied, transmitted via facsimile, and/or scanned-in to an electronic document processing system. Moreover, for at least some applications, the glyphs desirably are composed of printed pixel patterns containing nearly the same number of ON pixels and nearly the same number of OFF pixels, such that the code that is rendered by printing such glyphs on substantially uniformly spaced centers appears to have a generally uniform texture. In the case of codes printed at higher spatial densities, this texture is likely to be perceived as a generally uniform gray tone.