IMAGE PROCESSING METHOD AND IMAGE PROCESSING APPARATUS

Abstract

An image processing method and image processing apparatus which can execute vector conversion processing by appropriately dividing a clipart image including gradation into regions are provided. To this end, a color document image including a clipart image having an area of gradation is input, the clipart image is selected, and outline information of the clipart image is extracted. The color document image is separated into an achromatic color area and a chromatic color area, which are respectively divided into a plurality of regions. Of the plurality of regions of each of the achromatic color area and the chromatic color area divided in the dividing of region step, regions which meet a set condition are integrated. After that, the clipart image is converted into vector data using a region group after integrating of region and the outline information.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a block diagram showing the arrangement of an image processing apparatus having a function of executing vector conversion processing based on region dividing according to the first embodiment of the present invention;

FIGS. 2A and 2B are flowcharts for explaining an overview of the vector conversion processing based on region dividing of a clipart image according to the first embodiment of the present invention;

FIG. 3 shows an example of a clipart image selected from a document image in image processing according to the first embodiment of the present invention;

FIG. 4 is a flowchart for explaining details of edge cluster forming processing in step S15 in FIGS. 2A and 2B;

FIG. 5 shows an example of an edge cluster formed based on the clipart image according to the first embodiment of the present invention;

FIG. 6 is a flowchart for explaining details of separation processing of achromatic and chromatic color areas in step S17 in FIGS. 2A and 2B;

FIG. 7 is a flowchart for explaining details of region dividing processing of an achromatic color area in step S18 in FIGS. 2A and 2B;

FIG. 8 is a flowchart for explaining details of region integrating processing of an achromatic color area in step S20 in FIGS. 2A and 2B;

FIG. 9 shows an example of noise to be handled in the image processing according to the first embodiment of the present invention;

FIG. 10 is a flowchart for explaining details of re-processing of a noise region in step S23 in FIGS. 2A and 2B;

FIG. 11 is a flowchart for explaining details of edge cluster determination processing in step S24, and details of edge cluster integrating processing in step S25 in FIGS. 2A and 2B;

FIG. 12 shows an example in which a cluster is determined as an edge cluster from divided clusters and is integrated to an edge cluster according to the first embodiment of the present invention;

FIGS. 13A to 13C show an example of vector conversion based on region dividing of a clipart image according to the first embodiment of the present invention;

FIG. 14 is a block diagram showing the arrangement of an image processing apparatus which executes vector conversion processing of an image with gradation according to the second embodiment of the present invention;

FIG. 15 is a flowchart for explaining vector conversion processing based on region dividing according to the second embodiment;

FIG. 16 is a flowchart for explaining details of region dividing processing of an image with gradation according to the second embodiment of the present invention;

FIG. 17 shows an image example in the region dividing processing according to the second embodiment;

FIG. 18 shows eight types of masks corresponding to color change directions, i.e., edge directions in the second embodiment;

FIG. 19 shows color change directions of respective pixels calculated by color change direction detection processing in the second embodiment for a certain linear gradation region (horizontal direction) and certain radial gradation region;

FIG. 20 is a view for explaining details of intersection detection processing according to the second embodiment;

FIG. 21 is a view for explaining vector description processing in the second embodiment;

FIGS. 22A and 22B show a description result of certain region 1 as a linear gradation region, and that of certain region 2 as a radial gradation region after an image with gradation is divided into regions;

FIG. 23 is a block diagram showing the arrangement of an image processing apparatus which executes vector conversion processing of an image with gradation according to the third embodiment of the present invention;

FIG. 24 is a flowchart for explaining processing according to the third embodiment of the present invention;

FIG. 25 is a block diagram showing the arrangement of an image processing apparatus which executes linear gradation determination processing according to the fourth embodiment of the present invention;

FIG. 26 is a flowchart for explaining image processing in the image processing apparatus according to the fourth embodiment of the present invention;

FIG. 27 shows an example of linear gradation description processing according to the fourth embodiment of the present invention; and

FIG. 28 is a block diagram showing the arrangement of principal parts of a digital multi function peripheral (MFP) as an embodiment which implements the image processing apparatus shown in FIG. 1.

Claims

1. An image processing method in an image processing apparatus for inputting a color document image including a clipart image having an area of gradation, and converting the clipart image into vector data, comprising: a selecting step of selecting the clipart image from the input color document image;an extracting step of extracting outline information of the clipart image;a separating step of separating the color document image into an achromatic color area and a chromatic color area;a dividing of region step of respectively dividing the achromatic color area and the chromatic color area into a plurality of regions;an integrating of region step of integrating regions which meet a set condition of the plurality of regions of each of the achromatic color area and the chromatic color area divided in the dividing of region step; anda converting step of converting the clipart image into vector data using region groups integrated in the integrating of region step and the outline information.

2. The method according to claim 1, wherein the separating step comprises: a color converting step of converting the color document image from an RGB color space into an HSV color space; andan achromatic color area/chromatic color area separating step of separating the color document image into the achromatic color area and the chromatic color area based on color information on the HSV color space of the color document image.

3. The method according to claim 1, wherein the dividing of region step comprises: a first setting step of setting brightness values used in dividing of region of the achromatic color area of the color document image;a second setting step of setting color information used in dividing of region of the chromatic color area of the color document image;an achromatic color area dividing of region step of dividing a region in which a difference between brightness values falls within a predetermined value range as an identical region, and a region in which the difference falls outside the predetermined value range as another region of the regions in the achromatic color area of the color document image; anda chromatic color area dividing of region step of dividing a region in which a difference between two pieces of color information falls within a predetermined value range as an identical region, and a region in which the difference falls outside the predetermined value range as another region of the regions in the chromatic color area of the color document image.

4. The method according to claim 3, wherein the color information is RGB color information, and the difference between the two pieces of color information is a Euclidean distance.

5. The method according to claim 1, wherein the integrating of region step comprises: a first setting step of setting a threshold of a brightness value distance used in integrating of region of the achromatic color area of the color document image;a second setting step of setting thresholds of an RGB information distance and hue distance used integrating of region of the chromatic color area of the color document image;an achromatic color area integrating of region step of integrating regions when a brightness value distance between the plurality of divided regions of the achromatic color area is not more than the threshold; anda chromatic color area integrating of region step of integrating regions when a RGB information distance and hue distance between the plurality of divided regions of the chromatic color area are respectively not more than the thresholds.

6. The method according to claim 1, wherein the clipart image is an illustration image or a graphic image.

7. An image processing method in an image processing apparatus for inputting a document image including an image with gradation, and converting the image into vector data, comprising: a dividing of region step of dividing the image into regions;a labeling step of labeling the regions obtained by dividing the image;a gradation type determining step of determining gradation types of the labeled regions in the image; anda description step of describing the regions using a graphic language in accordance with the determined gradation types.

8. The method according to claim 7, wherein the gradation type determining step comprises: a color change direction detecting step of detecting color change directions of pixels in each region;a linear gradation determining step of determining, when the color change directions agree with an identical direction, gradation in the region as linear gradation; anda radial gradation determining step of determining, when the color change directions do not agree with the identical direction, gradation in the region as radial gradation.

9. The method according to claim 7, wherein the gradation type determining step comprises: a color change direction detecting step of detecting color change directions of pixels in each region;an intersection detecting step of detecting an intersection of direction vectors of the color change directions;a radial gradation determining step of determining, when the intersection of the direction vectors is detected, gradation in the region as radial gradation; anda linear gradation determining step of determining, when the intersection of the direction vectors is not detected, gradation in the region as linear gradation.

10. The method according to claim 9, wherein the intersection detecting step comprises: a barycenter detecting step of detecting a barycenter of a region of pixels having the same direction vector;a vector extracting step of a direction vector from the barycenter as a representative vector of the region;an inter-vector intersection detecting step of detecting an intersection between arbitrary two direction vectors; anda gradation intersection detecting step of determining, when the intersection between the two direction vectors falls within a predetermined distance range, that a gradation intersection is present in the region, and determining the intersection as a gradation intersection.

11. The method according to claim 8, further comprising: a color maximum value/minimum value detecting step of detecting a maximum value and a minimum value of a color in the region determined as the linear gradation in the linear gradation determining step; anda linear gradation pattern determining step of determining a density pattern of the color of the linear gradation based on color values of two pixels located on a straight line including a first pixel position where the detected maximum value of the color is located, and a second pixel position where the minimum value is located.

12. An image processing apparatus for inputting a color document image including a clipart image having an area of gradation, and converting the clipart image into vector data, comprising: a selecting unit adapted to select the clipart image from the input color document image;an extracting unit adapted to extract outline information of the clipart image;a separating unit adapted to separate the color document image into an achromatic color area and a chromatic color area;a dividing of region unit adapted to respectively divide the achromatic color area and the chromatic color area into a plurality of regions;an integrating of region unit adapted to integrate regions which meet a set condition of the plurality of regions of each of the achromatic color area and the chromatic color area divided by said dividing of region unit; anda converting unit adapted to convert the clipart image into vector data using region groups integrated by said integrating of region unit and the outline information.

13. An image processing apparatus for inputting a document image including an image with gradation, and converting the image into vector data, comprising: a dividing of region unit adapted to divide the image into regions;a labeling unit adapted to label the regions obtained by dividing the image;a gradation type determining unit adapted to determine gradation types of the labeled regions in the image; anda description unit adapted to describe the regions using a graphic language in accordance with the determined gradation types.

14. A program, stored in a computer-readable storage medium, for making a computer execute an image processing method according to claim 1.

15. A computer-readable storage medium storing a program according to claim 14.