Image processing apparatus and method
AssigneeCanon Kabushiki Kaisha
InventorToshinori Igari
Life of this patent
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Abstract
Entered image data is stored in a page buffer on a per-page basis, and image data that has been stored in the page buffer is subjected to error diffusion processing on a per-raster basis, thereby creating and outputting binarized data. Sub-scanning direction error due to error diffusion processing is stored in an error buffer at the time of binarization. The error buffer is initialized based upon positions, in the sub-scanning direction, of a raster that underwent error diffusion processing immediately previously and a raster to undergo error diffusion processing, and the number of rasters on a page. As a result, it is possible to avoid a deterioration in image quality at page boundaries and at the beginning of an image simultaneously when data for printing on elongated sheets of paper is processed.
Claims12
An image processing apparatus comprising:
- a page buffer for storing entered image data on a per-page basis;
- and
- binarizing means for subjecting image data, which has been stored in said page buffer, to error diffusion processing on a per-raster basis, thereby generating binarized data, and outputting the binarized data, wherein
- said binarizing means includes:
- an error buffer for storing sub-scanning direction error due to the error diffusion processing;
- and
- error-buffer initializing means for initializing said error buffer based upon positions, in the sub-scanning direction, of a raster that underwent error diffusion processing immediately previously and a raster to undergo error diffusion processing, and number of rasters on a page.
An image processing method comprising:
- a page buffering step of storing entered image data in a page buffer on a per-page basis;
- and
- a binarizing step of subjecting image data, which has been stored in said page buffer, to error diffusion processing on a per-raster basis, thereby generating binarized data, and outputting the binarized data, wherein
- said binarizing step includes:
- an error buffering step of storing subscanning direction error due to the error diffusion processing in an error buffer;
- and
- an error-buffer initializing step of initializing said error buffer based upon positions, in the sub-scanning direction, of a raster that underwent error diffusion processing immediately previously and a raster to undergo error diffusion processing, and number of rasters on a page.
A printer driver installed in a host device connected to a printer, comprising code of a program for implementing the following steps:
- a page buffering step of storing entered image data in a page buffer on a per-page basis;
- and
- a binarizing step of subjecting image data, which has been stored in said page buffer, to error diffusion processing on a per-raster basis, thereby generating binarized data, and outputting the binarized data, wherein
- said binarizing step includes:
- an error buffering step of storing sub-scanning direction error due to the error diffusion processing in an error buffer;
- and
- an error-buffer initializing step of initializing said error buffer based upon positions, in the sub-scanning direction, of a raster that underwent error diffusion processing immediately previously and a raster to undergo error diffusion processing, and number of rasters on a page.
A storage medium storing a printer driver installed in a host device connected to a printer, comprising code of a program for implementing the following steps:
- a page buffering step of storing entered image data in a page buffer on a per-page basis;
- and
- a binarizing step of subjecting image data, which has been stored in said page buffer, to error diffusion processing on a per-raster basis, thereby generating binarized data, and outputting the binarized data, wherein
- said binarizing step includes:
- an error buffering step of storing subscanning direction error due to the error diffusion processing in an error buffer;
- and
- an error-buffer initializing step of initializing said error buffer based upon positions, in the sub-scanning direction, of a raster that underwent error diffusion processing immediately previously and a raster to undergo error diffusion processing, and number of rasters on a page.
Dependencies are inferred from the claim text.