IMAGE PROCESSING APPARATUS FOR DISCRIMINATING IMAGE FIELD OF ORIGINAL DOCUMENT PLURAL TIMES AND METHOD THEREFOR

• US 20010016065A1
• Filed: 08/20/1998
• Published: 08/23/2001
• Est. Priority Date: 08/20/1997
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: YAMAMOTO, NAOFUMI, KAWAKAMI, HARUKO, RAO, GURURAJ
• Granted Patent: US 6,424,742 B2
• Time in Patent Office: Days
• US Class Current: 382/173
• CPC Class Codes: G06T 2207/10008 from scanner, fax or copier
• CPC Class Codes: G06T 2207/30176 Document
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06V 30/10 Character recognition
• CPC Class Codes: G06V 30/162 Quantising the image signal
• CPC Class Codes: G06V 30/18105 related to colour
• CPC Class Codes: G06V 30/414 Extracting the geometrical structure, e.g. layout tree; Block segmentation, e.g. bounding boxes for graphics or text

Abstract

An image processing apparatus incorporating a field separating section for separating an original image into plural types of fields in response to a first image signal obtained at a rough density of the supplied original image, a characteristic value calculating section for calculating a characteristic value of the original image in response to a second image signal of the original image obtained at a density which is higher than the rough density, and a discrimination section for discriminating an image field of the original image in accordance with the characteristic value to correspond to the type of the field.

Claims

1. An image processing apparatus comprising:

field separating means for separating an original image into plural types of fields in response to a first image signal obtained at a first density of the original image;

characteristic value calculating means for calculating a characteristic value of the original image in response to a second image signal of the original image obtained at a second density which is higher than the first density;

discrimination means for discriminating an image field of the original image in accordance with the characteristic value calculated by the characteristic value calculating means to correspond to the type of the field by the field separated by the separating means; and

an image processing means for processing a predetermined image processes corresponding to a result of discrimination of the image field performed by the discrimination means, on the second image signal.

2. An image processing apparatus according to

claim 1

, wherein each of the field separation means and the characteristic value calculating means further includes scanning means for scanning the original image at the first density and then scanning the same at the second density.

3. An image processing apparatus according to

claim 1

, wherein the field separating means includes

means for separating the original image into at least a usual character field, characters on a background, a continuous gradation field and a dot gradation field.

4. An image processing apparatus according to

claim 1

, wherein means is provided which deletes a gradation image existing in a field which has not been discriminated by the field separating means as a gradation field and a gradation image existing in a field discriminated as a continuous gradation field.

5. An image processing apparatus according to

claim 1

, wherein the characteristic value calculating means includes

characteristic value calculating means for calculating change in the density, an average density and chroma which are characteristic values of the original image in response to the second image signal of the original image obtained at the second density which is higher than the first density.

6. An image processing apparatus according to

claim 1

, wherein the characteristic value calculating means includes

characteristic value calculating means for calculating a characteristic value of the original image in each of unit regions having different lengths in a main scanning direction and a sub-scanning direction in response to the second image signal of the original image obtained at the second density which is higher than the first density.

7. An image processing apparatus according to

claim 1

, wherein the discrimination means includes

second discrimination means for discriminating the image field of the original image by means of comparing the characteristic value calculated by the characteristic value calculating means with a threshold value corresponding to the type of the field separated by the separating means.

8. An image processing apparatus according to

claim 1

, wherein the characteristic value calculating means includes

a second characteristic value calculating means for calculating a segment component of the original image in a main scanning direction and a sub-scanning direction as the characteristic value in response to the second image signal of the original image obtained at the second density which is higher than the first density.

9. An image processing method comprising the steps of:

a field separating step for separating an original image into plural types of fields in response to a first image signal obtained at a first density of the supplied original image;

a characteristic value calculating step for calculating a characteristic value of the original image in response to a second image signal of the original image obtained at a second density which is higher than the first density;

a discrimination step for discriminating an image field of the original image in accordance with the characteristic value calculated in the characteristic value calculating step to correspond to the type of the field separated in the field separating step; and

an image processing step for processing a predetermined image processes corresponding to a result of discrimination of the image field performed by the discrimination means, on the second image signal.

10. An image processing method according to

claim 9

, wherein each of the field separation step and the characteristic value calculating step further includes a scanning step for scanning the original image at the first density and then scanning the same at the second density.

11. An image processing method according to

claim 9

, wherein the field separating step includes

a step for separating the original image into at least a usual character field, characters on a background, a continuous gradation field and a dot gradation field.

12. An image processing method according to

claim 9

, wherein a step is provided which deletes a gradation image existing in a field which has not been discriminated in the field separating step as a gradation field and a gradation image existing in a field discriminated as a continuous gradation field.

13. An image processing method according to

claim 9

, wherein the characteristic value calculating steps includes

a characteristic value calculating step for calculating change in the density, an average density and chroma which are characteristic values of the original image in response to the second image signal of the original image obtained at the second density which is higher than the first density.

14. An image processing method according to

claim 9

, wherein the characteristic value calculating step includes

a characteristic value calculating step for calculating a characteristic value of the original image in each of unit regions having different lengths in a main scanning direction and a sub-scanning direction in response to the second image signal of the original image obtained at the second density which is higher than the first density.

15. An image processing method according to

claim 9

, wherein the discrimination step includes

a second discrimination step for discriminating the image field of the original image by means of comparing the characteristic value calculated by the characteristic value calculating step with a threshold value corresponding to the type of the field separated by the separating step.

16. An image processing method according to

claim 9

, wherein the characteristic value calculating step includes

a second characteristic value calculating step for calculating a segment component of the original image in a main scanning direction and a sub-scanning direction as the characteristic value in response to the second image signal of the original image obtained at the second density which is higher than the first density.