Color image processing apparatus

• US 5,047,844 A
• Filed: 03/22/1989
• Issued: 09/10/1991
• Est. Priority Date: 03/24/1988
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ohnishi, Tetsuya, Ikeda, Yoshinori, Shimizu, Masatomo
• Primary Examiner(s): Britton, Howard W.
• Application Number:
  US07/327,098
• Time in Patent Office: 902 Days
• Field of Search: 358/75, 358/79, 358/80, 358/81
• US Class Current: 358/521
• CPC Class Codes: H04N 1/58 Edge or detail enhancement; Noise or error suppression, e.g. colour misregistration correction H04N1/62 takes precedence

Abstract

An edge portion of an achromatic area is detected to emphasize the edge portion and reduce the density of a chromatic area near the edge portion, and the reduced chromatic portion signal is further suppressed, such that the half tone area can be processed at high gradation and the black character and line image can be outputted with more black and high resolution, resulting in less color bleeding.

Claims

1. A color image processing apparatus comprising:

(a) discriminating means for discriminating an achromatic and line image portion within an image;

(b) reducing means for reducing a chromatic color component within an area near said achromatic and line image portion discriminated by said discriminating means; and

(c) suppressing means for suppressing a chromatic color component reduced by said reducing means.

2. A color image processing apparatus according to claim 1, wherein said suppressing means is means for further smoothing said chromatic color component reduced by said reducing means.

3. A color image processing apparatus according to claim 1, further comprising:

(d) means for supplying said chromatic color component suppressed by said suppressing means to a color printing device.

4. A color image processing apparatus according to claim 1, wherein said suppressing means suppresses the chromatic color component reduced by said reducing means to a fixed value.

5. A color image processing apparatus according to claim 1, wherein said discriminating means includes:

(a) first discriminating means for discriminating an achromatic portion within the image;

(b) second discriminating means for discriminating a line image portion within the image;

(c) third discriminating means for discriminating an achromatic and line image portion in accordance with a combination of discrimination results obtained by said first and second discriminating means.

6. A color image processing apparatus according to claim 5, wherein said second discriminating means discriminates said line image portion through discrimination of an edge within the image.

7. A color image processing apparatus according to claim 1, further comprising means for converting an object color image into an electric signal and supplying said electric signal to said discriminating means.

8. A color image processing apparatus according to claim 7, further comprising means for supplying said chromatic color component reduced by said suppressing means.

9. A color image processing apparatus comprising:

(a) detecting means for detecting an achromatic and line image portion of an image;

(b) means responsive to a detection by said detecting means for emphasizing an edge portion of said achromatic and line image portion and reducing a chromatic color component within an area near said achromatic and line image portion; and

(c) suppressing means for suppressing a chromatic color component reduced by said reducing means.

10. A color image processing apparatus according to claim 9, wherein said detecting means includes:

(a) first discriminating means for discriminating an achromatic portion within the image;

(b) second discriminating means for discriminating a line image portion within the image;

(c) third discriminating means for discriminating an achromatic and line image portion in accordance with a combination of discrimination results obtained by said first and second discriminating means.

11. A color image processing apparatus according to claim 9, further comprising means for converting an object color image into an electric signal and supplying said electric signal to said detecting means.

12. A color image processing apparatus according to claim 9, wherein said suppressing means is means for further smoothing said chromatic color component reduced by said reducing means.

13. A color image processing apparatus according to claim 9, wherein said suppressing means suppresses the chromatic color component reduced by said reducing means to a fixed value.

14. A color image processing apparatus according to claim 9, further comprising means for supplying said chromatic color component reduced by said suppressing means.

15. A color image copying apparatus comprising:

(a) a color image sensor for converting an object image into a color image signal;

(b) processing means for processing said color image signal converted by said color image sensor, said processing means including;

(c) discriminating means for discriminating an achromatic and line image portion within the object image;

(d) reducing means for reducing a chromatic color component within an area near said achromatic and line image portion discriminated by said discriminating means; and

(e) suppressing means for suppressing a chromatic color component reduced by said reducing means; and

(f) a color printer for independently forming a chromatic color image and an achromatic image, respectively, of said color image signal processed by said processing means.

16. A color image copying apparatus according to claim 15, wherein said color image sensor is provided with color filters aligned on a line and having different transmission characteristics.

17. A color image copying apparatus according to claim 15, wherein said color printer forms a black image for an achromatic signal, and yellow, magenta and cyan images for chromatic color signals.

18. A color image copying apparatus according to claim 15, wherein said discriminating means includes:

(a) first discriminating means for discriminating an achromatic portion within the object image;

(b) second discriminating means for discriminating a line image portion within the object image;

(c) third discriminating means for discriminating an achromatic and line image portion in accordance with a combination of discrimination results obtained by said first and second discriminating means.