| 摘要 |
A printer-system for printing or recording images using a plurality of dots having different densities. The printer system includes a head for producing at least 2 different types of dots having different densities per unit area, an input unit for receiving input tone data with respect to each of the pixels in an original image, a threshold value storage unit for storing threshold values, a multi-valuing unit for determining the on-off state of a dot and the type of the dot to be created at each pixel, and a dot creation unit for driving the printer head. Print image quality is degraded for example when, around any specific input tone value, there are abrupt changes in the number density of large dots to small dots. The multi-valuing unit, employing error diffusion techniques, changes the threshold values for selecting the type of dot printed to control the relative density of large dots at each input tone value and thus regulates the print image quality.
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