SPATIAL SAMPLING OF PRINTED PATTERNS

The bitmap obtained by scanning a printed pattern depends on the exact location of the scanning grid relative to the pattern. We consider id eal sampling with a regular lattice of delta functions. The displaceme nt of the lattice relative to the pattern is random and obeys a unifor m probability density function defined over a unit cell of the lattice . Random-phase sampling affects the edge-pixels of sampled patterns. T he resulting number of distinct bitmaps and their relative frequencies can be predicted from a mapping of the original pattern boundary to t he unit cell (called a module-grid diagram). The theory is supported b y both simulated and experimental results. The module-grid diagram may be useful in helping to understand the effects of edge-pixel variatio n on Optical Character Recognition.