Image forming apparatus and image forming method

• US 7,706,022 B2
• Filed: 06/12/2006
• Issued: 04/27/2010
• Est. Priority Date: 06/12/2006
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Tec Corporation (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation), Toshiba Tec Corporation (Toshiba Corporation)
• Inventors: Okuyama, Hiroyuki
• Primary Examiner(s): Lee; Thomas D
• Assistant Examiner(s): Brinich; Stephen M
• Application Number:
  US11/451,524
• Publication Number:
  US 20070285525A1
• Time in Patent Office: 1,415 Days
• Field of Search: 358/2.1, 358/1.9, 358516-520, 358/504, 358529-530, 358/448, 358/461, 358/3.23
• US Class Current: 358/2.1
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence

Abstract

An image forming apparatus according to the invention is characterized by including; an input unit that inputs first color data; a first color converting unit that converts the first color data into a black single color data; a second color converting unit that converts the first color data into second color data; a brightness correcting unit that corrects brightness of the black single color data such that brightness of the black single color data converted by the first color converting unit is equal to brightness of the second color data converted by the second color converting unit; and an image forming unit that prints image data on a recording medium. According to the image forming apparatus, in the image forming apparatus that uses both color conversion processing and black conversion processing, even if image data continuously changes from a chromatic color to an achromatic color, it is possible to reduce “brightness discontinuity”.

Claims

1. An image forming apparatus comprising:

an input unit configured to input first color data;

a first color converting unit configured to convert the first color data into black single color data;

a second color converting unit configured to convert the first color data into second color data;

a brightness correcting unit configured to correct brightness of the black single color data such that brightness of the black single color data converted by the first color converting unit is equal to brightness of the second color data converted by the second color converting unit;

an image forming unit configured to print image data on a recording medium;

an achromatic color determining unit configured to determine whether achromatic color data is included in the first color data; and

a switching unit configured to output, when it is determined by the achromatic color determining unit that achromatic color data is included, the black single color data, brightness of which is corrected by the brightness correcting unit, to the image forming unit as the image data and output, when it is determined by the achromatic color determining unit that achromatic color data is not included, the second color data to the image forming unit as the image data.

2. An image forming apparatus according to claim 1, wherein the brightness correcting unit corrects brightness of the black single color data according to a lookup table.

3. An image forming apparatus according to claim 1, wherein the second color converting unit is configured to be capable of converting a color according to at least one of a method of converting a color giving higher priority to emphasis of chroma than coincidence of brightness and a method of converting a color giving higher priority to emphasis of contrast than coincidence of brightness in addition to a method of converting the first color data such that brightness of the first color data and brightness of the second color data are equal.

4. An image forming apparatus according to claim 1, wherein

the input unit includes an object determining unit configured to determine whether an “

object”

of the first color data is at least anyone of a “

character object”

, a “

graphic object”

, and an “

image object”

, and

the switching unit outputs, when it is determined by the object determining unit that the “

object”

of the first color data is the “

character object”

or the “

graphic object” and

it is determined by the achromatic color determining unit that achromatic data is included, the black single color data, brightness of which is corrected by the brightness correcting unit, to the image forming unit as the image data.

5. An image forming method comprising:

inputting first color data;

converting the first color data into black single color data;

converting the first color data into second color data;

correcting brightness of the black single color data such that brightness of the black single color data is equal to brightness of the second color data;

printing image data on a recording medium;

determining whether achromatic color data is included in the first color data; and

outputting, when it is determined in the achromatic color determining step that achromatic color data is included, the black single color data, brightness of which is corrected in the brightness correcting step, as the image data and outputting, when it is determined in the achromatic color determining step that achromatic color data is not included, the second color data as the image data.

6. An image forming method according to claim 5, wherein, in correcting brightness, brightness of the black single color data is corrected according to a lookup table.

7. An image forming method according to claim 5, wherein, in converting the first color data into second color data, a color is converted according to at least one of a method of converting a color giving higher priority to emphasis of chroma than coincidence of brightness and a method of converting a color giving higher priority to emphasis of contrast than coincidence of brightness in addition to a method of converting the first color data such that brightness of the first color data and brightness of the second color data are equal.

8. An image forming method according to claim 5, wherein

the step of inputting includes a step of determining whether an “

object”

of the first color data is at least any one of a “

character object”

, a “

graphic object”

, and an “

image object”

, wherein

in the step of outputting, the black single color data, brightness of which is corrected in the brightness correcting step, is outputted as the image data when it is determined in the object determining step that the “

object”

of the first color data is the “

character object”

or the “

graphic object” and

it is determined in the achromatic color determining step that achromatic data is included.