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US 6,633,412 B1Granted
Smoothness enhancement in laser printing through periodic modulation of halftone cell
AssigneeSeiko Epson Corporation
InventorsTsung-Nan Lin, Joseph Shu
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AssigneeSeiko Epson Corporation
InventorsTsung-Nan Lin, Joseph Shu
Estimating the term…
When clustered-dot dithering is employed in laser printers a banding effect sometimes results from the interaction of the dither matrix with non-uniform line spacing in the printer. We have found that we can lessen the effect of this interaction if we change the dither matrix as it moves over the image. We do this by modulating the dither matrix (halftone cell) as a function of the spatial position of the sub-area in the image. Halftone cells can be formed in a variety of patterns (e.g. vertical, horizontal, etc.) but generally their threshold values grow from a minimum value to a maximum value. Our process is to modulate the halftone cell according to a function: f (s, h) where s is the spatial position of the sub-area of the image and h is the halftone cell. We modulate the cell by altering the relative positions of the threshold values in the cell as we move the cell over the image. This effectively breaks up the bands of clusters of one size or another and provides a visually uniform image even in lighter tones.
An image processing apparatus comprising:
A method operating an image processing system, comprising:
A medium readable by a machine embodying a program of instructions executable by said machine to perform a method of operating an image processing system, said method comprising:
An image processing system comprising:
Dependencies are inferred from the claim text.