Color conversion method

A color conversion method for converting a color signal for an image output device into a color signal in a color space for color matching, comprising:

• a first acquisition step of acquiring a color signal of an image output device;
• a first conversion step of converting the color signal into a color signal A on a colorimetric color space;
• a second conversion step of acquiring a color signal P of gray for the image output device at a lightness of the color signal A;
• a determination step of determining whether or not the color signal A is contained in a low-saturation area containing the color signal P and a color signal O of calorimetrically achromatic color at a lightness of the color signal A;
• a third acquisition step of acquiring a color signal B that is an intersection between a line segment connecting the color signal P and the color signal A and the outermost contour of the low-saturation area, when it is determined that the color signal A is contained in the low-saturation area at said determination step;
• a second conversion step of converting the color signal A into a color signal D in accordance with a conversion function of converting the color signal on the line segment connecting the color signal B and the color signal P into the color signal on the line segment connecting the color signal B and the color signal O;
• and
• an output step of outputting the color signal D.

A color conversion method for converting a color signal of a predetermined image output device into a color signal in a color mapping color space that is a common color space for mutually converting the color signals of plural kinds of image output devices, comprising:

• a first conversion step of converting the color signal of the predetermined image output device into a color signal A in a uniform color space;
• a determination step of determining whether the color signal A exists inside a low-saturation area R that is set in the uniform color space;
• and
• a second conversion step of converting the color signal A in the uniform color space into the color signal in the color mapping color space,
• wherein said second conversion step comprises converting the color signal A into the color signal on a line segment connecting the color signal that is achromatic color in the uniform color space and an outermost contour of the low-saturation area R when the color signal A exists inside the low-saturation area R, and outputting the color signal A without conversion, when the color signal A exists outside the low-saturation area R.

A profile creation device for creating the profile data for mutually converting a color signal of a predetermined image output device into a color signal in a color mapping color space that is a common color space for mutually converting the color signals of plural kinds of image output devices, comprising:

• first conversion means for converting a discrete color signal C of the predetermined image output device into a color signal A in a uniform color space;
• a determination means for determining whether the color signal A exists inside a low-saturation area that is set in the uniform color space;
• second conversion means for converting the color signal A into a color signal D in the color mapping color space;
• and
• profile creation means for creating a profile from the correspondent information between the discrete color signal C and the color signal D,
• wherein said second conversion means converts the color signal A into the color signal on a line segment connecting the color signal that is achromatic color in the uniform color space and a outermost contour of the low-saturation area R when the color signal A exists inside the low-saturation area R, and outputs the color signal A without conversion into the color signal on the line segment connecting the color signal that is achromatic color in the uniform color space and the outermost contour of the low-saturation area R when the color signal A exists outside the low-saturation area R.

A profile creation method for creating the profile data for mutually converting a color signal of a predetermined image output device and a color signal in a color mapping color space that is a common color space for mutually converting the color signals of plural kinds of image output devices, comprising:

• a first conversion step of converting a discrete color signal C of the predetermined image output device into a color signal A in a uniform color space;
• a determination step of determining whether the color signal A exists inside a low-saturation area that is set in the uniform color space;
• a second conversion step of converting the color signal A into a color signal D in the color mapping color space;
• and
• a profile creation step of creating a profile from the correspondent information between the discrete color signal C and the color signal D;
• wherein said second conversion step comprises converting the color signal A into the color signal on a line segment connecting the color signal that is achromatic color in the uniform color space and the outermost contour of the low-saturation area R when the color signal A exists inside the low-saturation area that is set in the uniform color space, and outputting the color signal A without converting into the color signal on the line segment connecting the color signal that is achromatic color in the uniform color space and a outermost contour of a low-saturation area R when the color signal A exists outside the low-saturation area that is set in the uniform color space.