Image processing method and image processing apparatus

An image processing apparatus for converting a color input image or a partial region thereof in accordance with a color gamut of a color image output apparatus, comprising:

• an output color gamut point calculation part that determines a color gamut point as an intersection between a base line that is a line extending from a fixed point in the color gamut of said output apparatus to a conversion target point and an output color gamut surface as a color gamut surface of the color gamut or a closed curved surface in the color gamut of said output apparatus;
• an input color gamut point calculation part that determines an input color gamut point as an intersection between said base line and an input color gamut surface as the color gamut surface of the color gamut of said input image or said partial region thereof;
• a first conversion point calculation part that determines a first conversion point on said base line using said fixed point, said output color gamut point and a first weighing coefficient;
• a second conversion point calculation part that determines a second conversion point by using correction data for correcting a compressing direction or an expanding direction and said first weighing coefficient;
• and
• a final conversion point calculation part that determines a final conversion point for said conversion target point by using said first conversion point, said second conversion point and a second weighing coefficient.

An image processing method of converting a color input image or a partial region thereof in accordance with a color gamut of a color image output apparatus, wherein said conversion processing in accordance with the color gamut of said output apparatus is conducted while correcting the direction and the extent of compression/expansion by using correction data, comprising:

• a first conversion point calculation step of compressing or expanding a conversion target point to a point on a line connecting a fixed point in the color gamut of said output apparatus, that can be determined uniquely based on said conversion target point, with said conversion target point thereby calculating a first conversion point;
• a second conversion point calculation step of calculating a correction point by using correction data corresponding to said conversion target point and compressing or expanding said correction point to a point on a line connecting said fixed point with said correction point thereby calculating a second conversion point;
• and
• a final conversion point calculation step of determining a final conversion point for said conversion target point by using said first conversion point and said second conversion point.

An image processing method of converting a color input image or a partial region thereof in accordance with a color gamut of a color image output apparatus, wherein said conversion processing in accordance with the color gamut of said output apparatus is conducted while correcting the direction and the extent of compression/expansion by using correction data, comprising:

• a correction point calculation step for correcting a conversion target point and calculating a correction point by using correction data corresponding to said conversion target point;
• a compression/expansion processing step of compressing or expanding a correction point to a point on a line connecting a fixed point in the color gamut of said output apparatus, that is determined uniquely based on said conversion target point, with said correction point;
• and
• an inverse correction point calculation step of correcting said conversion point or said second conversion point calculated by compressing or expanding the correction point based on inversion correction data corresponding to said conversion point or said second conversion point.

An image processing apparatus for converting a color input image or a partial region thereof in accordance with a color gamut of a color image output apparatus, comprising:

• a correction point calculation part that calculates a correction point by correcting a conversion target point using correction data corresponding to said conversion target point;
• and
• a compression/expansion processing part that calculates a conversion point by compressing or expanding a correction point to a point on a line connecting a fixed point in a color gamut of said output apparatus that can be determined uniquely based on said conversion target point with said correction point,
• wherein the apparatus comprises an inversion correction point calculation part that corrects said conversion point or said second conversion point calculated by compressing or expanding the correction point based on inverse correction data corresponding to said conversion point or said second conversion point.