Image processing apparatus, image processing method and image forming apparatus

Abstract

An image processing apparatus includes an input section and a binarizing section. The input section inputs multilevel image data. The binarizing section binarizes multilevel image data to generate output image data representing halftone dots each having a hollow-structure. The binarizing section enlarges the halftone dots in a predetermined direction preferentially in accordance with the input multilevel image data.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an overall configuration of an image forming apparatus according to a first exemplary embodiment of the invention;

FIG. 2A to 2H is a view showing an example of a halftone dot represented in 64 gradations of 6 bits;

FIGS. 3A and 3B are graphs for explaining characteristic of threshold data used for forming gap by a binarizing section; the binarizing section;

FIG. 5 is a flow chart showing the outline of a procedure of halftone-dot processing in the binarizing section;

FIG. 6 is a view showing processes of production of ring-like halftone dots by halftone-dot processing in the binarizing section;

FIGS. 7A and 7B are views showing a halftone-dot image generated by halftone-dot processing in the binarizing section and a halftone-dot image generated by binarizing processing according to the related art;

FIG. 8 is a diagram showing an overall configuration of an image forming apparatus according to a second exemplary embodiment;

FIG. 9 is a block diagram showing the configuration of a binarizing section;

FIG. 10 is a block diagram showing the configuration of a modulation control section;

FIG. 11 is a flow chart showing the outline of a procedure of halftone-dot processing in an image processing section;

FIG. 12 is a view showing processes of production of ring-like halftone dots by halftone-dot processing in the image processing section; and

FIG. 13A is a view schematically showing an example of binarizing processing according to the related art; and FIG. 13B is a view showing an example of halftone dots generated by the binarizing processing.

Claims

1. An image processing apparatus comprising: an input section that inputs multilevel image data; anda binarizing section that binarizes multilevel image data to generate output image data representing halftone dots each having a hollow-structure, the binarizing section that enlarges the halftone dots in a predetermined direction preferentially in accordance with the input multilevel image data.

2. The apparatus according to claim 1, wherein the binarizing section makes the halftone dots larger preferentially in the predetermined direction as a density of the input multilevel image data gets larger.

3. The apparatus according to claim 1, wherein the binarizing section generates the output image data, which represents the halftone-dot pattern having a substantially linear structure when a value of the multilevel image data is in a predetermined range.

4. The apparatus according to claim 1, wherein: the input section inputs the plural pieces of multilevel image data of a plurality of color components,the binarizing section generates the plural pieces of output image data,each of the output image data represents the hollow-structure halftone-dot pattern, which is enlarged preferentially in the direction of the predetermined angle, andthe predetermined angles of the respective color components are different from each other.

5. An image processing apparatus comprising: an input section that inputs multilevel image data; anda binarizing section that binarizes multilevel image data to generate output image data representing halftone dots each having a hollow-structure, the binarizing section that enlarges the halftone dots in a predetermined direction preferentially in accordance with the input multilevel image data, wherein:the binarizing section generates the output image data so that: a hollow portion formed inside the halftone-dot pattern is enlarged until a value of the multilevel image data reaches a predetermined range, andthat the hollow portion is reduced when the value of the multilevel image data exceeds the predetermined range.

6. The apparatus according to claim 1, wherein the binarizing section comprises: a first image-data generating section that generates first image data representing a set of pixel dots, which are enlarged preferentially in the direction of the predetermined angle in accordance with a value of the multilevel image data input from the input section;a second image-data generating section that generates second image data representing a set of non-pixel dots located inside the set of pixel dots represented by the first image data, the set of non-pixel dots being enlarged or reduced accordance with the value of the multilevel image data input from the input section; andan arithmetic processing section that generates the output image data based on the first image data generated by the first image-data generating section and the second image data generated by the second image-data generating section.

7. The apparatus according to claim 6, wherein the second image-data generating section generates the second image data when the value of the multilevel image data input from the input section is equal to or larger than a predetermined value.

8. The apparatus according to claim 6, wherein the second image-data generating section generates the second image data so that the set of non-pixel dots does not overlap a contour portion of the set of pixel dots.

9. An image processing method for binarizing multilevel image data to generate output image data, which is used to reproduce halftones in a pseudo manner, the method comprising: inputting multilevel image data;generating the output image data representing a hollow-structure halftone-dot pattern, which is enlarged preferentially in a direction of a predetermined angle in accordance with the multilevel image data input from the input section; andoutputting the generated output image data.

10. The method according to claim 9, wherein the generating of the output image data comprises: generating first image data representing a set of pixel dots, which are enlarged preferentially in the direction of the predetermined angle in accordance with a value of the input multilevel image data;generating second image data representing a set of non-pixel dots located inside the set of pixel dots represented by the first image data, the set of non-pixel dots being enlarged or reduced preferentially in the direction of the predetermined angle in accordance with the value of the input multilevel image data; andgenerating the output image data based on the generated first image data and the generated second image data.

11. The apparatus according to claim 1, wherein the binarizing section enlarges each halftone dot in accordance with the input multilevel image data so that an angle between a line having a screen angle and an average of vectors, which connect a center of the halftone dot and a contour point of the halftone dot farthest from the center, is in a predetermined range.

12. An image processing apparatus comprising: an input section that inputs multilevel image data; anda binarizing section that binarizes the multilevel image data to generate output image data representing a hollow-structure halftone-dot pattern, in which a number of pixel dots in a predetermined region extending in a direction of a specific angle is larger than that of any other region having the same area as the predetermined region.

13. An image forming apparatus comprising: an input section that inputs multilevel image data;a binarizing section that binarizes the multilevel image data to generate output image data representing halftone dots each having a hollow-structure, the binarizing section that enlarges the halftone dots in a predetermined direction preferentially in accordance with the input multilevel image data; andan image forming section that forms a halftone image based on the output image data generated by the binarizing section.

14. The apparatus to claim 13, wherein the binarizing section generates the output image data, which represents the halftone-dot pattern having a substantially linear structure when a value of the multilevel image data is in a predetermined range.

15. The apparatus according to claim 14, wherein: the input section inputs the plural pieces of multilevel image data of a plurality of color components,the binarizing section generates the plural pieces of output image data,each of the output image data represents the hollow-structure halftone-dot pattern, which is enlarged preferentially in the direction of the predetermined angle, andthe predetermined angles of the respective color components are different from each other.

16. The apparatus according to claim 13, wherein the binarizing section comprises: a first image-data generating section that generates first image data representing a set of pixel dots, which are enlarged preferentially in the direction of the predetermined angle in accordance with a value of the multilevel image data input from the input section;a second image-data generating section that generates second image data representing a set of non-pixel dots located inside the set of pixel dots represented by the first image data, the set of non-pixel dots being enlarged or reduced preferentially in the direction of the predetermined angle in accordance with the value of the multilevel image data input from the input section; andan arithmetic processing section that generates the output image data based on the first image data generated by the first image-data generating section and the second image data generated by the second image-data generating section.

17. The apparatus according to claim 16, wherein: the image forming section applies a coloring agent to a recording medium to form the halftone image, andthe image forming section controls an amount of the applied coloring agent based on the second image data generated by the second image-data generating section.

18. The apparatus according to claim 16, wherein: the image forming section applies a coloring agent to a recording medium to form the halftone image, andthe image forming section prohibits the coloring agent from being applied based on the second image data generated by the second image-data generating section.