IMAGE PROCESSING APPARATUS AND IMAGE PROCESSING METHOD

• US 20160134780A1
• Filed: 10/13/2015
• Published: 05/12/2016
• Est. Priority Date: 11/11/2014
• Status: Active Grant

• Current Assignee: Konica Minolta Inc.
• Original Assignee: Konica Minolta Inc.
• Inventors: GENDA, Daisuke
• Granted Patent: US 9,456,106 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04N 1/387 Composing, repositioning or otherwise geometrically modifying originals
• CPC Class Codes: H04N 1/405 Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
• CPC Class Codes: H04N 1/407 Control or modification of tonal gradation or of extreme levels, e.g. background level
• CPC Class Codes: H04N 1/4092 Edge or detail enhancement

Abstract

An image processing apparatus includes a contour extracting unit, a contour processing unit, a dithering unit and a binarizing unit. The contour extracting unit extracts a contour pixel forming a contour part from pixels of image data having multiple gradation values. The contour processing unit performs adjustment to reduce a gradation value of the contour pixel extracted by the contour extracting unit. The dithering unit binarizes, by using a blue noise dither matrix, the gradation value of the contour pixel subjected to the adjustment by the contour processing unit. The binarizing unit binarizes, of the pixels of the image data, a gradation value of a non-contour pixel which is other than the contour pixel.

Claims

1. An image processing apparatus comprising:

a contour extracting unit which extracts a contour pixel forming a contour part from pixels of image data having multiple gradation values;

a contour processing unit which performs adjustment to reduce a gradation value of the contour pixel extracted by the contour extracting unit;

a dithering unit which binarizes, by using a blue noise dither matrix, the gradation value of the contour pixel subjected to the adjustment by the contour processing unit; and

a binarizing unit which binarizes, of the pixels of the image data, a gradation value of a non-contour pixel which is other than the contour pixel.

2. The image processing apparatus according to claim 1, wherein the contour processing unit (i) identifies, of the extracted contour pixel, a contour pixel which generates a step of two or more pixels in the contour part if a gradation value becomes a minimum gradation value by the binarization by the dithering unit and (ii) adjusts the gradation value of the identified contour pixel to a maximum gradation value.

4. The image processing apparatus according to claim 1, wherein

the contour processing unit identifies, of the extracted contour pixel, a contour pixel which generates a step of two or more pixels in the contour part if a gradation value becomes a minimum gradation value by the binarization by the dithering unit, and

the dithering unit outputs a maximum gradation value as the gradation value of the identified contour pixel.

5. The image processing apparatus according to claim 2, wherein the contour processing unit performs the identification by comparing (a) the extracted contour pixel and an adjacent pixel which is adjacent to the extracted contour pixel with (b) a contour part pattern having a step of two or more pixels.

6. The image processing apparatus according to claim 2, wherein the contour processing unit reduces a gradation value of an adjacent pixel which is adjacent to the identified contour pixel.

3. The image processing apparatus according to claim herein the contour processing unit (i) identifies, of the extracted contour pixel, a contour pixel which generates a step of two or more pixels in the contour part if a gradation value becomes a minimum gradation value by the binarization by the dithering unit and (ii) invalidates the adjustment to reduce the gradation value of the contour pixel with respect to the identified contour pixel.

7. An image processing method comprising:

extracting a contour pixel forming a contour part from pixels of image data having multiple gradation values;

performing adjustment to reduce a gradation value of the extracted contour pixel;

binarizing, by using a blue noise dither matrix, the gradation value of the contour pixel subjected to the adjustment; and

binarizing, of the pixels of the image data, a gradation value of a non-contour pixel which is other than the contour pixel.