Color signal processing device, image processing apparatus, color signal processing method, image processing method, computer-readable medium and computer data signal

1. A color signal processing device comprising:

a conversion unit that converts a first color signal into a second color signal, wherein

the second color signal is obtained by changing a color point, in a device independent color space, corresponding to a color of each color component of the first color signal by a distance corresponding to a reduction degree so that the color point, in the device independent color space, corresponding to the color of each color component of the first color signal approaches white along a locus, in the device independent color space, corresponding to each color component of the first color signal, and

the locus, in the device independent color space, corresponding to each color component is obtained by changing an amount of a coloring material that corresponds to each color component and is used in an output device.

2. The device according to claim 1 , wherein the color components of the first color signal includes ones selected from the group consisting of (i) cyan, magenta, yellow and black, (ii) cyan, magenta and yellow and (iii) red, green and blue.

3. The device according to claim 1 , further comprising:

an accepting unit that accepts setting of the reduction degree, wherein

the conversion unit converts the first color signal into the second color signal according to the reduction degree accepted by the accepting unit.

4. The device according to claim 1 , wherein the conversion unit changes the distance according to an area in the device independent color space where a color point corresponding to the first color signal exists.

5. The device according to claim 1 , wherein the conversion unit changes the distance so that a reduction amount of each coloring material increases with increase in chroma or with decrease in lightness.

6. The device according to claim 1 , wherein the conversion unit changes the changing amount of the distance so that a reduction amount of each coloring material becomes larger as the first color signal is closer to a maximum chroma point or as the first color signal is closer to a minimum lightness point.

7. The device according to claim 1 , wherein the conversion unit changes the distance in accordance with a characteristic type of the first color signal.

8. The device according to claim 1 , wherein the conversion unit changes the distance in accordance with an intended use of the second color signal.

9. The device according to claim 1 , further comprising:

a color space conversion unit that converts a third color signal in the device independent color space into the first color signal having, as constituent elements, the coloring materials used in the output device.

10. The device according to claim 1 , further comprising:

a color space conversion unit that converts a plurality of third color signals in the device independent color space into a plurality of the first color signals having, as constituent elements, the coloring materials used in the output device; and

a conversion coefficient generating unit that generates conversion coefficients using a plurality of color signal pairs, which associate the second color signals obtained by converting the first color signals by the conversion unit with the third color signals, the conversion coefficients for converting a color signal in the device independent color space into another color signal in a device dependent color space having, as constituent elements, the coloring materials used in the output device when the coloring materials are reduced.

11. An image processing apparatus comprising:

a storage unit that stores the conversion coefficients generated by the color signal processing device according to claim 10 ; and

a color signal conversion unit that converts a color signal of a device independent color space into a color signal of a device dependent color space using the conversion coefficients stored in the storage unit.

12. A non-transitory computer-readable medium storing a program that causes a computer to execute color signal processing, the color signal processing comprising:

converting a first color signal into a second color signal, wherein

the second color signal is obtained by changing a color point, in a device independent color space, corresponding to each color component of the first color signal by a distance corresponding to a reduction degree so that the color point, in the device independent color space, corresponding to each color component of the first color signal approaches white along a corresponding locus, in the device independent color space, corresponding to each color component of the first color signal, and

the locus, in the device independent color space, corresponding to each color component is obtained by changing an amount of a coloring material that corresponds to each color component and is used in an output device.

13. A non-transitory computer-readable medium storing a program that causes a computer to execute image signal processing, the image signal processing comprising:

storing the conversion coefficients generated by the color signal processing device according to claim 10 ; and

converting a color signal of a device independent color space into a color signal of a device dependent color space using the stored conversion coefficients.

14. A color signal processing method comprising:

converting a first color signal into a second color signal, wherein

the second color signal is obtained by changing a color point, in a device independent color space, corresponding to each color component of the first color signal by a distance corresponding to a reduction degree so that the color point, in the device independent color space, corresponding to each color component of the first color signal approaches white along a corresponding locus, in the device independent color space, corresponding to each color component of the first color signal, and

the locus, in the device independent color space, corresponding to each color component is obtained by changing an amount of a coloring material that corresponds to each color component and is used in an output device.

15. An image signal processing method comprising:

converting a first color signal into a second color signal, wherein

the second color signal is obtained by changing a color point, in a device independent color space, corresponding to a color of each color component of the first color signal by a distance corresponding to a reduction degree so that the color point, in the device independent color space, corresponding to the color of each color component of the first color signal approaches white along a locus, in the device independent color space, corresponding to each color component of the first color signal, and

the locus, in the device independent color space, corresponding to each color component is obtained by changing an amount of a coloring material that corresponds to each color component and is used in an output device;

converting a plurality of third color signals in the device independent color space into a plurality of the first color signals having, as constituent elements, the coloring materials used in the output device;

generating the conversion coefficients using a plurality of color signal pairs, which associate the second color signals with the third color signals, the conversion coefficients suitable for converting a color signal in the device independent color space into another color signal in a device dependent color space having, as constituent elements, the coloring materials used in the output device when the coloring materials are reduced;

storing the conversion coefficients generated by the color signal processing device; and

converting a color signal of a device independent color space into a color signal of a device dependent color space using the stored conversion coefficients.