Method and apparatus for slow scan magnification adjustment using non-redundant overwriting
AssigneeXerox Corporation
InventorsBeilei Xu, Robert P. Loce, Jess R. Gentner
Life of this patent
Estimating the term…
Abstract
A method of achieving process-direction sub-raster magnification adjustment using non-redundant overwriting. The raster imager provides overwriting while the image path provides non-redundant data for each pass according to the desired magnification adjustment. The same laser power level can be used for the multiple writes, or optionally, it may be varied to further improve spatial resolution of the adjustment.
Claims20
A method of achieving process-direction sub-raster magnification:
- correction using non-redundant overwriting, the method comprising:
- determining process-direction magnification errors on both sides of a printed sheet and a magnification compensation factor for the printed sheet;
- receiving raster data from a digital image path;
- buffering the raster data in a raster memory for overwriting a swath of pixel data;
- extracting raster data from the buffer according to a plurality of non-redundant overwriting (NRO) resampling calculations for magnification correction;
- and
- using the extracted raster data to drive a raster imager.
An apparatus for achieving process-direction sub-raster magnification adjustments using non-redundant overwriting, the apparatus comprising:
- an image-forming apparatus that includes a raster imager;
- and
- a control device for controlling the image-forming apparatus, wherein the control device is operative to:
- determine process-direction magnification errors on both sides of a printed sheet and a magnification compensation factor for the printed sheet;
- receive raster data from a digital image path;
- buffer the raster data in a raster memory for overwriting a swath of pixel data;
- extract raster data from the buffer according to a plurality of non-redundant overwriting (NRO) resampling calculations for magnification correction;
- and
- use the extracted raster data to drive the raster imager.
A computer program product comprising:
- a computer-usable data carrier storing instructions that, when executed by a computer, cause the computer to perform a method comprising:
- determining process-direction magnification errors on both sides of a printed sheet and a magnification compensation factor for the printed sheet;
- receiving raster data from a digital image path;
- buffering the raster data in a raster memory for overwriting a swath of pixel data;
- extracting raster data from the buffer according to a plurality of non-redundant overwriting (NRO) sampling calculations for magnification correction;
- and
- using the extracted raster data to drive a raster imager
The computer program product of claim 20, wherein the compensation factor for the print is determined by at least one of the following methods:
- offline characterization of paper shrinkage for individual media type or average characterization over a range of media, wherein the offline characterizations are stored and pulled into active use when the appropriate media is being printed;
- real-time measurement of paper size;
- and real-time velocity measurement of printer components.
Dependencies are inferred from the claim text.