Ink Jet Printing Apparatus, Image Processing Apparatus, And Method For Processing Image

Abstract

An ink jet printing apparatus which inhibits possible bleeding by thinning color data adjacent to black data and enables printing free from image quality degradation such as gradation skip is provided. Specifically, when only one pixel has color data and pixels located vertically and horizontally adjacent to that pixel have no color data, an isolated point pixel containing a color dot is detected only in that pixel. Then, the dots other than the isolated point are thinned-out. This makes it possible to inhibit possible bleeding at the boundary between a color area and a black area and to achieve proper printing with the appropriate gradation of the entire image maintained.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically showing the configuration of a color ink jet printer in accordance with an embodiment of the present invention;

FIG. 2 is a perspective view schematically showing the configuration of an essential part of a print head 201 shown in FIG. 1;

FIG. 3 is a block diagram showing a control arrangement in the color ink jet printer in accordance with an embodiment of the present invention;

FIG. 4 is a diagram showing a relation between FIGS. 4A and 4B, and FIGS. 4A and 4B are block diagrams showing a process for generating print data for respective colors which process includes a thinning process in accordance with an embodiment of the present invention;

FIG. 5 is a flowchart showing a process for detecting one-dot-neighborhood-of-black pixels;

FIGS. 6A to 6D are diagrams illustrating an example of detection of one-dot-neighborhood-of-black pixels;

FIG. 7 is a flowchart showing an isolated point removal detection process of removing isolated points from cyan data;

FIGS. 8A to 8C are diagrams illustrating an example of detection in sensing for removal of isolated points from cyan data;

FIG. 9 is a flowchart showing an isolated point removal detection process of removing isolated points from magenta data;

FIGS. 10A to 10C are diagrams illustrating an example of detection in sensing for removal of isolated points from magenta data;

FIG. 11 is a flowchart showing an isolated point removal detection process of removing isolated points from yellow data;

FIGS. 12A to 12C are diagrams illustrating an example of detection in sensing for removal of an isolated point from magenta data;

FIG. 13 is a block diagram showing the configuration of a process for selecting a thinning-out object color;

FIGS. 14A to 14D are diagrams illustrating an example of selection of a thinning-out object color;

FIGS. 15A to 15G are diagrams illustrating a process for determining the amounts of thinning-out object color data shown in FIG. 14D using respective color masks 1;

FIG. 16 is a flowchart showing a process for processing mostly printing color data; and

FIGS. 17A to 17K are diagrams showing data generated by the data generating process in FIG. 16.

Claims

1. An ink jet printing apparatus that generates print data based on image data arranging a plurality of pixels including pixels having black data and color data and performs printing by applying black ink and color ink to a print medium, said apparatus comprising: detection means for detecting color data pixels that are not isolated point pixels, in which predetermined number of or more pixels are not consecutively arranged in a predetermined direction in the arrangement of pixels, and that are pixels located in neighborhoods of pixels having black data in the image data, in pixels having color data; andgenerating means for generating printing data for color by thinning-out color data of the color data pixels detected by said detection means.

2. An ink jet printing apparatus as claimed in claim 1, wherein, if a logical AND of a logical OR of color data of adjacent pixels located above and below and to the right and left of an object pixel and color data of the object pixel is a predetermined value, in pixel matrix of L×M (L, M=1, 3, 5, . . . , n, n+2, where n is a natural number) containing the object pixel as a center pixel of the matrix, said detection means detects the object pixel as isolated pixel.

3. An ink jet printing apparatus as claimed in claim 1, wherein said detection means includes neighborhood-of-black pixel detection means that detects neighborhood pixels of pixels having black data in the image data, and perform the detection by executing a logical AND operation of the neighborhood pixels of pixels having black data which are detected by said neighborhood-of-black pixel detection means and pixels having color data that are not the isolated point pixels.

4. An ink jet printing apparatus as claimed in claim 3, wherein said neighborhood-of-black pixel detection means detects the neighborhood pixels of the pixels having black data by executing logical AND operation of pixels having black data and neighborhood pixels of the pixels having black data in the image data and inverted pixels of the pixels having black data in the image data.

5. An ink jet printing apparatus as claimed in claim 3, wherein said neighborhood-of-black pixel detection means counts a number of black dots in a pixel matrix of L×M (L, M=1, 3, 5, . . . , n, n+2, where n is a natural number) containing a object pixel as center pixel of the matrix, and detects the object pixel as a neighborhood pixel of pixel having black data in the image data if the counted value is greater than a predetermined value.

6. An ink jet printing apparatus as claimed in claim 1, further comprising thinning-out object color selection means for selecting colors for which thinning-out is executed, said thinning-out object color selection means selecting a thinning-out object color data from a combination of data for yellow, magenta and cyan in the image data.

7. An ink jet printing apparatus that generates print data based on image data arranging a plurality of pixels including pixels having black data and color data and performs printing by applying black ink and color ink to a print medium, said apparatus comprising: isolated point pixel detection means for detecting isolated point pixels, in which a predetermined number of or more pixels are not consecutively arranged in a predetermined direction in the arrangement of pixels, in pixels having color data;neighborhood-of-black pixel detection means for detecting neighborhood pixels of pixels having black data of the image data, in the pixels having color data;thinning means for thinning the color data; andgenerating means for generating printing data for color ink by thinning-out color data of the neighborhood pixels of pixels having black data.

8. An ink jet printing apparatus as claimed in claim 7, wherein said generation means generates printing data by not thinning-out the isolated point pixels.

9. An ink jet printing apparatus as claimed in claim 7, wherein said generation means generates printing data by thinning-out a part of the isolated point pixels.

10. An ink jet printing apparatus as claimed in claim 7, wherein said generation means generates printing data by thinning-out pixels that are a small area of pixels in which smaller number of pixels than a second number that is smaller than the predetermined number are consecutively arranged and are the neighborhood pixels of the pixels having black data.

11. An image processing apparatus that generates print data based on image data arranging a plurality of pixels including pixels having black data and color data and performs printing by applying black ink and color ink to a print medium, said apparatus comprising: detection means for detecting color data pixels that are not isolated point pixels, in which predetermined number of or more pixels are not consecutively arranged in a predetermined direction in the arrangement of pixels, and that are pixels located in neighborhoods of pixels having black data in the image data, in pixels having color data; andgenerating means for generating printing data for color by thinning-out color data of the color data pixels detected by said detection means.

12. An image processing method of generating print data based on image data arranging a plurality of pixels including pixels having black data and color data and performs printing by applying black ink and color ink to a print medium, said apparatus comprising: a detection step of detecting color data pixels that are not isolated point pixels, in which predetermined number of or more pixels are not consecutively arranged in a predetermined direction in the arrangement of pixels, and that are pixels located in neighborhoods of pixels having black data in the image data, in pixels having color data; anda generating step of generating printing data for color by thinning-out color data of the color data pixels detected by said detection step.

13. An image processing method as claimed in claim 12, wherein, if a logical AND of a logical OR of color data of adjacent pixels located above and below and to the right and left of an object pixel and color data of the object pixel is a predetermined value, in pixel matrix of L×M (L, M=1, 3, 5, . . . , n, n+2, where n is a natural number) containing the object pixel as a center pixel of the matrix, said detection step detects the object pixel as isolated pixel.

14. An image processing method as claimed in claim 12, wherein said detection step includes neighborhood-of-black pixel detection step that detects neighborhood pixels of pixels having black data in the image data, and perform the detection by executing a logical AND operation of the neighborhood pixels of pixels having black data which are detected by said neighborhood-of-black pixel detection step and pixels having color data that are not the isolated point pixels.

15. An image processing method as claimed in claim 14, wherein said neighborhood-of-black pixel detection step detects the neighborhood pixels of the pixels having black data by executing logical AND operation of pixels having black data and neighborhood pixels of the pixels having black data in the image data and inverted pixels of the pixels having black data in the image data.

16. An image processing method as claimed in claim 15, wherein said neighborhood-of-black pixel detection step counts a number of black dots in a pixel matrix of L×M (L, M=1, 3, 5, . . . , n, n+2, where n is a natural number) containing a object pixel as center pixel of the matrix, and detects the object pixel as a neighborhood pixel of pixel having black data in the image data if the counted value is greater than a predetermined value.

17. An image processing method as claimed in claim 12, further comprising thinning-out object color selection step for selecting colors for which thinning-out is executed, said thinning-out object color selection step selecting a thinning-out object color data from a combination of data for yellow, magenta and cyan in the image data.

18. A program causing a computer to function as an image processing apparatus that generates print data based on image data arranging a plurality of pixels including pixels having black data and color data and performs printing by applying black ink and color ink to a print medium, said function comprising: detection means for detecting color data pixels that are not isolated point pixels, in which predetermined number of or more pixels are not consecutively arranged in a predetermined direction in the arrangement of pixels, and that are pixels located in neighborhoods of pixels having black data in the image data, in pixels having color data; andgenerating means for generating printing data for color by thinning-out color data of the color data pixels detected by said detection means.