Color image processing apparatus, image processing apparatus, color image processing method, image processing method, and a computer-readable recording medium for making a computer execute the methods

An image processing apparatus comprising:

• a plane signal conversion unit which converts an image signal expressed on a color space to an image signal on a plane;
• a chroma identification unit which identifies a chroma of the image signal based on the image signal converted by said plane signal conversion unit;
• a hue area identification unit which identifies a hue of the image signal based on the image signal converted by said plane signal conversion unit;
• and
• a color conversion unit which executes color conversion of the image signal expressed on the color space based on a signal input from said chroma identification unit and a signal input from said hue area identification unit.

An image processing apparatus comprising:

• a plane signal conversion unit which converts an image signal expressed on a color space to an image signal on a plane;
• a chroma identification unit which identifies a chroma of the image signal based on the image signal converted by said plane signal conversion unit;
• a hue area identification unit which identifies a hue of the image signal based on the image signal converted by said plane signal conversion unit;
• a masking coefficient selection unit which selects an optimal masking coefficient for the image signal based on a signal input from said chroma identification unit and a signal input from said hue area identification unit;
• and
• a color conversion unit which executes color conversion of the image signal expressed on the color space based on a result of selection by said masking coefficient selection unit.

A color image processing method comprising:

• a plane signal conversion step at which a plane signal is generated by converting a color space expressed by an input color image signal to a plane;
• a chroma identification step at which a chroma identification signal is generated by identifying a chroma of the color image signal based on the plane signal generated at the plane signal conversion step;
• a hue area identification step at which a hue area is identified in the color image signal based on the plane signal generated at the plane signal conversion step and a hue area identification signal is generated;
• and
• a color conversion step at which color conversion of the color image signal is executed based on the chroma identification signal generated at the chroma identification step and the hue area identification signal generated at the hue area identification step.

An image processing method comprising:

• a plane signal conversion step at which an image signal expressed on a color space is converted to an image signal on a plane;
• a chroma identification step at which a chroma of the image signal is identified based on the image signal converted at the plane signal conversion step;
• a hue area identification step at which a hue of the image signal is identified based on the image signal converted at the plane signal conversion step;
• and
• a color conversion step at which color conversion of the image signal expressed on the color space is executed based on the signal identified at the chroma identification step and the signal identified at the hue area identification step.

An image processing method comprising:

• a plane signal conversion step at which an image signal expressed on a color space is converted to an image signal on a plane;
• a chroma identification step at which a chroma of the image signal is identified based on the image signal converted at the plane signal conversion step;
• a hue area identification step at which a hue of the image signal is identified based on the image signal converted at the plane signal conversion step;
• a masking coefficient selection step at which a masking coefficient optimal to an image based on the signal identified at the chroma identification step and a signal identified at the hue area identification step;
• and
• a color conversion step at which color conversion of the image signal expressed on the color space is executed based on the result of selection at the masking coefficient selection step.

A computer-readable recording medium in which a program for making a computer execute a color image processing method is recorded, said method comprising the steps of:

• a plane signal conversion at which a plane signal is generated by converting a color space expressed by an input color image signal to a plane;
• a chroma identification at which a chroma identification signal is generated by identifying a chroma of the color image signal based on the plane signal generated at the plane signal conversion step;
• a hue area identification at which a hue area is identified in the color image signal based on the plane signal generated at the plane signal conversion step and a hue area identification signal is generated;
• and
• a color conversion at which color conversion of the color image signal is executed based on the chroma identification signal generated at the chroma identification step and the hue area identification signal generated at the hue area identification step.

A computer-readable recording medium in which a program for making a computer execute an image processing method is recorded, said method comprising the steps of:

• a plane signal conversion at which an image signal expressed on a color space is converted to an image signal on a plane;
• a chroma identification at which a chroma of the image signal is identified based on the image signal converted at the plane signal conversion step;
• a hue area identification at which a hue of the image signal is identified based on the image signal converted at the plane signal conversion step;
• and
• a color conversion at which color conversion of the image signal expressed on the color space is executed based on the signal identified at the chroma identification step and the signal identified at the hue area identification step.