| 摘要 |
A printing device (10) is commanded to print a reference set of intensity values from almost white or highlight regions through almost dark or shadow regions. A measuring device (12) measures the actual outputted printe r intensity levels from the printing device (10). An interpolator (14) interpolates the printer intensity levels into a best fit smooth curve plotted against the reference set of intensity levels which produces a non-linear function. A mapping means an d converter (24a, 24b) calculate a set of fractional intensity values and densities which produce a linear function when mapped with the printer intensity levels. A d ot area parameter calculator (28) calculates a set of dot parameters defining a configuration of a halftone dot required to fill an area within the halftone cell corresponding to each intensity level. For each position of each halftone cell, a measurement processor (30) determines a distance between a current scan position (a,b) a nd a nearest edge defined by the dot parameters. A gray value calculator (50) calculates a gray value for the current scan position based on the distance and angle t o the nearest edge of the dot. The halftone dot is completed when a gray value is calculated for each position within the halftone cell. The gray values are stored in a look-up table (26). When a new image is to be printed, the intensity value s are input (54) and the scan position is indexed (52) through all available scan positions to generate corresponding addresses in the look-up table (26), causing the corresponding gray values to be output serially in order for use by a laser diode controller (56) of a laser printer or analogous controllers in other types o f printers.
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