Color discrimination apparatus and method

• US 6,480,624 B1
• Filed: 09/29/1998
• Issued: 11/12/2002
• Est. Priority Date: 09/30/1997
• Status: Expired due to Term

• Current Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Original Assignee: Minolta Co., Ltd. (Konica Minolta Inc.)
• Inventors: Horie, Daisaku, Okisu, Noriyuki
• Primary Examiner(s): Coles, Edward
• Assistant Examiner(s): Carter, Tia A
• Application Number:
  US09/163,266
• Time in Patent Office: 1,505 Days
• Field of Search: 382/165, 382/162, 382/163, 396/305, 348/713, 358/1.9, 358/218, 358/518, 358/403, 358/524
• US Class Current: 382/165
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 5/20 using local operators
• CPC Class Codes: G06T 5/70 Denoising; Smoothing
• CPC Class Codes: G06T 7/90 Determination of colour characteristics

Abstract

A color discriminating apparatus is provided with: a luminance calculator for calculating luminance information of a picked up color image based on image data of each of a plurality of color components constituting the color image; a color information calculator for calculating color information of the color image based on image data; a first discriminator for discriminating, based on calculated color information, which the color image is chromatic or achromatic; a second discriminator for discriminating, based on calculated luminance information, which the color image is black or white when the color image is discriminated to be achromatic; and a third discriminator for discriminating, based on the calculated color information and the calculated luminance information, which of a plurality of predetermined colors the color image agrees with when the color image is discriminated to be chromatic.

Claims

1. A color discriminating apparatus comprising:

a first calculator which calculates luminance information of a color image based on image data including a plurality of color components;

a second calculator which calculates color information of the color image based on image data;

a first discriminator which discriminates, based on the color information, whether the color image is chromatic or achromatic;

a second discriminator which discriminates, based on the luminance information, whether the color image is black or white when the color image is discriminated to be achromatic by the first discriminator; and

a third discriminator which discriminates, based on the color information and the luminance information, which of a plurality of predetermined colors corresponds with the color image when the color image is discriminated to be chromatic by the first discriminator.

2. A color discriminating apparatus according to claim 1, wherein the color information is calculated based on normalized data of second or higher powers of respective color component image data.

3. A color discriminating apparatus according to claim 1, wherein the plurality of color components includes three primary colors of red, blue, and green.

4. A color discriminating apparatus comprising:

a calculator which calculates normalized data x(i) of image data X(i) (i=1,2, . . . n) for each of a plurality of color components in accordance with the equation;

5. A color discriminating apparatus according to claim 4, wherein the plurality of color components includes three primary colors of red, blue, and green.

6. A color discriminating apparatus comprising:

a luminance information calculator which calculates luminance information of each part of a color image based on image data of a plurality of color components in each of the parts of the color image;

a color discriminator which discriminates the presence or absence of a discriminated color in each part of the color image by comparing calculated luminance information for each part with a discrimination reference;

an area information generator that generates area information related to a geometrical configuration of the color image; and

a changer which changes the discrimination reference based on generated area information.

7. A color discriminating apparatus comprising:

a color discriminator which discriminates a predominant color for each of a selected image section and a plurality of surrounding image sections in a color image based on image data of each of a plurality of color components;

a color dispersion degree calculator which calculates a degree of color dispersion for the selected image section using the predominant color of the selected image section and of the plurality of surrounding image sections;

a color dispersion degree discriminator which discriminates whether the degree of color dispersion is larger than a predetermined value; and

a black allocator which allocates the color of black to the selected image section when the color dispersion degree is discriminated to be larger than the predetermined value.

8. A color discriminating apparatus according to claim 7, wherein the black allocator further allocates the color of black to the plurality of color discriminated parts surrounding the particular part when the color dispersion degree is discriminated to be larger than the predetermined value.

9. A method for discriminating the color of a color image, comprising the steps of:

calculating luminance information of the color image based on image data of the color image including a plurality of color components;

calculating color information of the color image based on the image data;

discriminating, based on the color information, whether the color image is chromatic or achromatic;

discriminating, based on the luminance information, whether the color image is black or white when the color image is discriminated to be achromatic; and

discriminating, based on the color information and the luminance information, which of a plurality of predetermined colors corresponds with the color image when the color image is discriminated to be chromatic.

10. A method according to claim 9, wherein the color information is calculated based on normalized data of second or higher powers of respective color component image data.

11. A method according to claim 9, wherein the plurality of color components includes three primary colors of red, blue, and green.

12. A method for discriminating the color of a color image, comprising the steps of:

calculating normalized data x(i) of image data X(i) (i=1,2, . . . n) for each of a plurality of color components in accordance with the equation;

13. A method according to claim 12, wherein the plurality of color components includes three primary colors of red, blue, and green.

14. A method for discriminating the color of a color image, comprising the steps of:

calculating luminance information of each part of the color image based on image data of a plurality of color components in each part of the color image;

discriminating the presence or absence of a discriminated color in each part of of the color image by comparing calculated luminance information for each part with a discrimination reference;

generating area information related to a geometrical configuration of the color image; and

changing the discrimination reference based on generated area information.

15. A method for discriminating the color of color image, comprising the steps of:

discriminating a predominant color for each of a selected image section and a plurality of surrounding image sections in the color image based on image data of each of a plurality of color components constituting the selected image section and the plurality of surrounding image sections;

calculating a degree of color dispersion for the selected image section using the predominant color of the selected image section and of the plurality of surrounding image sections;

discriminating whether the degree of color dispersion is larger than a predetermined value; and

allocating the color of black to the selected image section when the color dispersion degree is discriminated to be larger than the predetermined value.

16. A method according to claim 15, wherein the plurality of surrounding image sections is allocated with the color of black when the degree of color dispersion is discriminated to be larger than the predetermined value.

17. A color allocating apparatus comprising:

a calculator which calculates a luminance and a chromatic value with respect to each of pixels composing a color image;

a discriminator which discriminates whether color of the pixel is white, black, or chromatic color based on the calculated luminance and the calculated chromatic value, referring to a predetermined discrimination threshold profile, wherein

the discrimination threshold profile allocates black or white to the pixel based on the luminance when the chromatic value is smaller than a predetermined value, and allocates white, chromatic color, or black based on the luminance when the chromatic value is larger than the predetermined value.

18. The apparatus according to claim 17, wherein the chromatic value is calculated based on values (xr, xg, xb) which are respectively obtained by standardizing Xr, Xg, Xb according to the following expressions when the color image is represented in terms of pixel values (Xr, Xg, Xb) respectively related to red, green, blue with respect to each of the pixels:

19. The apparatus according to claim 17, further comprising

an allocator which allocates one of predetermined colors to the pixel which is determined to allocate chromatic color according to the standardized values (xr, xg, xb).

20. A color allocating apparatus comprising:

a calculator which calculates a value x(i) (i=1,2, . . . , n) which is standardized for each of color components with respect to each of the pixels according to the following expression based on image data which is represented in terms of a plurality of color component values X(i) (i=1, 2, . . . , n) with respect to each of the pixels;

21. A color allocating apparatus comprising:

a configuration discriminator which discriminates whether a part constituting a color image is configured by a bold line having a width not smaller than a predetermined reference value or a thin line having a width smaller than the predetermined reference value;

a color discriminator which discriminates whether color of a pixel is white, black, or chromatic color according to a threshold value of the discriminated part based on a predetermined threshold value; and

an adjuster which changes the threshold value for discrimination by the color discriminator according to the configuration discriminated by the configuration discriminator.

22. The color allocating apparatus according to claim 21, wherein

said part corresponds to one pixel, and the configuration discriminator and the color discriminator make judgement with respect to each pixel of an image.

23. A color allocating apparatus comprising:

an allocator which allocates an allocated color from one of a predetermined plurality of colors that is close to the color of a pixel for each pixel of a color image;

a calculator which calculates a variation degree of the allocated color in a partial area composing a plurality of pixels in the color image; and

a re-allocator which reallocates the color of a target pixel corresponding to the partial area to black when it is judged that the variation degree is large.

24. The color allocating apparatus according to claim 23, wherein the target pixel is a pixel in the center of the partial area.

25. The color allocating apparatus according to claim 23, wherein the re-allocator reallocates the color of the plurality of pixels composing the partial area to black when it is judged that the variation degree is large.