| 摘要 |
A hyperacuity printing system includes a halftoner (20) which converts pixel intensity values into multi-bit gray values which drive a laser diode (62). The halftoner (20) includes a halftoner memory (22), a phase error look-up table (50), and a modulator (60). The halftoner memory (22) stores a pregenerated halftone dot pattern as a plurality of halftone dot planes or cells (24), each representing an intensity value. The halftoner memory (22) is addressed by the integer portion of a screen coordinate (x,y) and the intensity value, and outputs spatial coordinates (r, theta ) to an edge of the halftone dot nearest the screen coordinate. The fractional portion (xFRACT, yFRACT) of the screen coordinate (x,y) is combined with the outputted spatial coordinates (r, theta ) to provide corrected coordinates (rc, theta ). The corrected coordinates (rc, theta ) address a modulator drive function (56) which generates the multi-bit gray value used to drive the modulator (60). By combining the fractional portion of the screen coordinates with the halftoner memory data, automoire is corrected, and marks are rendered more accurately.
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