Image processing apparatus and image processing method

• US 20040109204A1
• Filed: 12/03/2003
• Published: 06/10/2004
• Est. Priority Date: 12/06/2002
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ono, Mitsuhiro, Yamada, Akitoshi, Kato, Masao
• Granted Patent: US 7,855,809 B2
• Time in Patent Office: Days
• US Class Current: 358/3.05
• CPC Class Codes: H04N 1/4057 the pattern being a mixture of differently sized sub-patterns, e.g. spots having only a few different diameters multi-toning H04N1/40087
• CPC Class Codes: H04N 1/52 Circuits or arrangements for halftone screening

Abstract

An image processing apparatus executes an error diffusion process to multivalue image data consisting of a plurality of density components. A first processor executes the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for the error diffusion process based on a value of the multivalue image data of the density components or a value calculated from the multivalue image data value. A second processor executes the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for the error diffusion process into fixed values. An error diffusion processing controller controls to execute the error diffusion process to at least one color among the density components by the first processor and execute the error diffusion process to other density components by the second processor.

Claims

1. An image processing apparatus for executing an error diffusion process to multivalue image data consisting of a plurality of density components, comprising:

first processing means for executing the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for said error diffusion process on the basis of a value of said multivalue image data of the density components or a value calculated from said multivalue image data value;

second processing means for executing the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for said error diffusion process into fixed values; and

error diffusion processing control means for making control to execute the error diffusion process to at least one color among said plurality of density components by said first processing means and execute the error diffusion process to other density components by said second processing means.

2. An apparatus according to claim 1, wherein said error diffusion processing control means executes the error diffusion process to the density components of a similar color among said plurality of density components by executing the error diffusion process to the density component whose highest density which can be expressed is low by said first processing means and executing the error diffusion process to the density component whose highest density which can be expressed is high by said second processing means.

3. An apparatus according to claim 1, wherein said first processing means is an error diffusion process for executing quantization on the basis of information of the other density components among said plurality of density components.

4. A print control apparatus for executing an error diffusion process to multivalue image data consisting of a plurality of density components, comprising:

first processing means for executing the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for said error diffusion process on the basis of a value of said multivalue image data of the density components or a value calculated from said multivalue image data value;

second processing means for executing the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for said error diffusion process into fixed values; and

error diffusion processing control means for making control to execute the error diffusion process to at least one color among said plurality of density components by said first processing means and execute the error diffusion process to other density components by said second processing means.

5. An apparatus according to claim 4, wherein said error diffusion processing control means executes the error diffusion process to the density components of a similar color among said plurality of density components by executing the error diffusion process to the density component whose highest density which can be expressed is low by said first processing means and executing the error diffusion process to the density component whose highest density which can be expressed is high by said second processing means.

6. An apparatus according to claim 4, wherein said first processing means is an error diffusion process for executing quantization on the basis of information of the other density components among said plurality of density components.

7. An image processing method of executing an error diffusion process to multivalue image data consisting of a plurality of density components, comprising:

a first processing step of executing the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for said error diffusion process on the basis of a value of said multivalue image data of the density components or a value calculated from said multivalue image data value;

a second processing step of executing the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for said error diffusion process into fixed values; and

an error diffusion processing control step of making control to execute the error diffusion process to at least one color among said plurality of density components by said first processing step and execute the error diffusion process to other density components by said second processing step.

8. A method according to claim 7, wherein in said error diffusion processing control step, the error diffusion process is executed to the density components of a similar color among said plurality of density components by executing the error diffusion process to the density component whose highest density which can be expressed is low by said first processing step and executing the error diffusion process to the density component whose highest density which can be expressed is high by said second processing step.

9. A method according to claim 7, wherein said first processing step is an error diffusion process for executing quantization on the basis of information of the other density components among said plurality of density components.

10. A print control method of executing an error diffusion process to multivalue image data consisting of a plurality of density components, comprising:

a first processing step of executing the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for said error diffusion process on the basis of a value of said multivalue image data of the density components or a value calculated from said multivalue image data value;

a second processing step of executing the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for said error diffusion process into fixed values; and

an error diffusion processing control step of making control to execute the error diffusion process to at least one color among said plurality of density components by said first processing step and execute the error diffusion process to other density components by said second processing step.

11. A method according to claim 10, wherein in said error diffusion processing control step, the error diffusion process is executed to the density components of a similar color among said plurality of density components by executing the error diffusion process to the density component whose highest density which can be expressed is low by said first processing step and executing the error diffusion process to the density component whose highest density which can be expressed is high by said second processing step.

12. A method according to claim 10, wherein said first processing step is an error diffusion process for executing quantization on the basis of information of the other density components among said plurality of density components.

13. A computer-readable storing medium which stores an image processing program for executing an error diffusion process to multivalue image data consisting of a plurality of density components, wherein said program comprises:

a first processing step of executing the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for said error diffusion process on the basis of a value of said multivalue image data of the density components or a value calculated from said multivalue image data value;

a second processing step of executing the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for said error diffusion process into fixed values; and

an error diffusion processing control step of making control to execute the error diffusion process to at least one color among said plurality of density components by said first processing step and execute the error diffusion process to other density components by said second processing step.

14. A medium according to claim 13, wherein in said error diffusion processing control step, the error diffusion process is executed to the density components of a similar color among said plurality of density components by executing the error diffusion process to the density component whose highest density which can be expressed is low by said first processing step and executing the error diffusion process to the density component whose highest density which can be expressed is high by said second processing step.

15. A medium according to claim 13, wherein said first processing step is an error diffusion process for executing quantization on the basis of information of the other density components among said plurality of density components.

16. A computer-readable storing medium which stores a print control program for executing an error diffusion process to multivalue image data consisting of a plurality of density components, wherein said program comprises:

a first processing step of executing the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for said error diffusion process on the basis of a value of said multivalue image data of the density components or a value calculated from said multivalue image data value;

a second processing step of executing the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for said error diffusion process into fixed values; and

an error diffusion processing control step of making control to execute the error diffusion process to at least one color among said plurality of density components by said first processing step and execute the error diffusion process to other density components by said second processing step.

17. A medium according to claim 16, wherein in said error diffusion processing control step, the error diffusion process is executed to the density components of a similar color among said plurality of density components by executing the error diffusion process to the density component whose highest density which can be expressed is low by said first processing step and executing the error diffusion process to the density component whose highest density which can be expressed is high by said second processing step.

18. A medium according to claim 16, wherein said first processing step is an error diffusion process for executing quantization on the basis of information of the other density components among said plurality of density components.

19. An image processing program for executing an error diffusion process to multivalue image data consisting of a plurality of density components, comprising:

a first processing step of executing the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for said error diffusion process on the basis of a value of said multivalue image data of the density components or a value calculated from said multivalue image data value;

a second processing step of executing the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for said error diffusion process into fixed values; and

an error diffusion processing control step of making control to execute the error diffusion process to at least one color among said plurality of density components by said first processing step and execute the error diffusion process to other density components by said second processing step.

20. A program according to claim 19, wherein in said error diffusion processing control step, the error diffusion process is executed to the density components of a similar color among said plurality of density components by executing the error diffusion process to the density component whose highest density which can be expressed is low by said first processing step and executing the error diffusion process to the density component whose highest density which can be expressed is high by said second processing step.

21. A program according to claim 19, wherein said first processing step is an error diffusion process for executing quantization on the basis of information of the other density components among said plurality of density components.

22. A print control program for executing an error diffusion process to multivalue image data consisting of a plurality of density components, comprising:

a first processing step of executing the error diffusion process by changing at least one of a quantization threshold value and a quantization diffusion coefficient which are used for said error diffusion process on the basis of a value of said multivalue image data of the density components or a value calculated from said multivalue image data value;

a second processing step of executing the error diffusion process by setting the quantization threshold value and the quantization diffusion coefficient which are used for said error diffusion process into fixed values; and

an error diffusion processing control step of making control to execute the error diffusion process to at least one color among said plurality of density components by said first processing step and execute the error diffusion process to other density components by said second processing step.

23. A program according to claim 22, wherein in said error diffusion processing control step, the error diffusion process is executed to the density components of a similar color among said plurality of density components by executing the error diffusion process to the density component whose highest density which can be expressed is low by said first processing step and executing the error diffusion process to the density component whose highest density which can be expressed is high by said second processing step.

24. A program according to claim 22, wherein said first processing step is an error diffusion process for executing quantization on the basis of information of the other density components among said plurality of density components.