Image forming apparatus that applies correction selectively to a subset of pixels
View Patent ↗An image forming apparatus includes a printing device, a storage device, in which unevenness correction data indicating a corrected pixel value in association with each input pixel value are stored, and a processor. The processor is configured to determine, among pixels indicated by raster image data of an image to be printed, edge pixels corresponding to an edge image portion and non-edge pixels corresponding to a non-edge image portion, carry out unevenness correction on the raster image data selectively with respect to the determined non-edge pixels, using the unevenness correction data stored in the storage device, generate print image data based on the raster image data subjected to the unevenness correction, and control the printing device to print the image based on the generated print image data.
1. An image forming apparatus, comprising:
a printing device;
a storage device, in which unevenness correction data indicating a corrected pixel value in association with each input pixel value are stored;
a processor configured to:
determine, among pixels indicated by raster image data of an image to be printed, edge pixels corresponding to an edge image portion and non-edge pixels corresponding to a non-edge image portion;
carry out unevenness correction on the raster image data selectively with respect to the determined non-edge pixels, using the unevenness correction data stored in the storage device;
generate print image data based on the raster image data subjected to the unevenness correction; and
control the printing device to print the image based on the generated print image data.
2. The image forming apparatus according to claim 1 , wherein
the processor generates the print image data by carrying out halftone processing on the raster image data subjected to the unevenness correction.
3. The image forming apparatus according to claim 1 , wherein
the processor does not carry out the unevenness correction with respect to the determined edge pixels.
4. The image forming apparatus according to claim 1 , further comprising:
a scanner, by which the raster image data are obtained as a result of scanning an original image.
5. The image forming apparatus according to claim 4 , wherein
the processor is further configured to generate the unevenness correction data based on test image data that is obtained by the scanner scanning a test image that includes a plurality of patch image regions arranged in a main scanning direction and a sub scanning direction, wherein patch image regions aligned in the sub scanning direction are of a same color and different pixel values that are incremental in the sub scanning direction.
6. The image forming apparatus according to claim 1 , wherein
the processor determines that pixels that have substantially the same pixel value and extend in a direction are edge pixels when a difference of a pixel value of one of the pixels and a pixel value of a pixel adjacent to the one of the pixels in a main scanning direction or a sub scanning direction is greater than a threshold value.
7. The image forming apparatus according to claim 1 , wherein
the unevenness correction data indicate, with respect to each of a plurality of image regions, a unique corrected pixel value in association with each input pixel value.
8. An image processing method comprising:
determining, among pixels indicated by raster image data of an image to be printed, edge pixels corresponding to an edge image portion and non-edge pixels corresponding to a non-edge image portion;
carrying out unevenness correction on the raster image data selectively with respect to the determined non-edge pixels, using unevenness correction data indicating a corrected pixel value in association with each input pixel value; and
generating print image data based on the raster image data subjected to the unevenness correction.
9. The image processing method according to claim 8 , wherein
the print image data are generated by carrying out halftone processing on the raster image data subjected to the unevenness correction.
10. The image processing method according to claim 8 , wherein
the unevenness correction is not carried out with respect to the determined edge pixels.
11. The image processing method according to claim 8 , further comprising:
obtaining the raster image data by scanning an original image by a scanner.
12. The image processing method according to claim 11 , further comprising:
generating the unevenness correction data based on test image data that are obtained by the scanner scanning a test image that includes a plurality of patch image regions arranged in a main scanning direction and a sub scanning direction, wherein patch image aligned in the main scanning direction are of a same color and different pixel values that are incremental in the sub scanning direction.
13. The image processing method according to claim 8 , wherein
pixels that have substantially the same pixel value and extend in a direction are edge pixels when a difference of a pixel value of one of the pixels and a pixel value of a pixel adjacent to the one of the pixels in a main scanning direction or a sub scanning direction is greater than a threshold value.
14. The image processing method according to claim 8 , wherein
the unevenness correction data indicate, with respect each of a plurality of image regions, a unique corrected pixel value in association with each input pixel value.
15. An image processing device comprising a processor configured to:
determine, among pixels indicated by raster image data of an image to be printed, edge pixels corresponding to an edge image portion and non-edge pixels corresponding to a non-edge image portion;
carry out unevenness correction on the raster image data selectively with respect to the determined non-edge pixels, using unevenness correction data indicating a corrected pixel value in association with each input pixel value; and
generate print image data based on the raster image data subjected to the unevenness correction.
16. The image processing device according to claim 15 , wherein
the processor generates the print image data by carrying out halftone processing on the raster image data subjected to the unevenness correction.
17. The image processing device according to claim 15 , wherein
the unevenness correction is not carried out with respect to the determined edge pixels.
18. The image processing device according to claim 15 , further comprising:
a scanner, by which the raster image data are obtained as a result of scanning an original image.
19. The image processing device according to claim 18 , wherein
the processor is further configured to generate the unevenness correction data based on test image data that are obtained by the scanner scanning a test image that includes a plurality of patch image regions arranged in a main scanning direction and a sub scanning direction, wherein patch image regions aligned in the sub scanning direction are of a same color and different pixel values that are incremental in the sub scanning direction.
20. The image processing device according to claim 15 , wherein
the processor determines that pixels that have substantially the same pixel value and extend in a direction are edge pixels when a difference of a pixel value of one of the pixels and a pixel value of a pixel adjacent to the one of the pixels in a main scanning direction or a sub scanning direction is greater than a threshold value.