Image processing device and image processing method performing color conversion processing using a lookup table

1. An image processing device that performs color conversion processing using a lookup table (LUT), comprising:

acquiring means for acquiring an emulation LUT for applying emulation of a gamut to a target device from a device in use, the emulation LUT being generated using (i) a device-in-use LUT for performing correction corresponding to input and output characteristics of the device in use and (ii) a target device LUT for performing correction corresponding to input and output characteristics of the target device;

generating means including first LUT arithmetic means for updating, for each lattice point forming the target device LUT, a value of the lattice point to a value obtained by gamut-converting the value of the lattice into a gamut of the device-in-use, and second LUT arithmetic means for updating a value of a lattice point forming the target device LUT updated by the first LUT arithmetic means to a value of a lattice point forming the device-in-use LUT,

wherein the second LUT arithmetic means finds, from the device-in-use LUT, a lattice point closest to the value of the lattice point forming the target device LUT updated by the first. LUT arithmetic means and updates a value of the lattice point found to the value of the lattice point forming the target device LUT updated by the first LUT arithmetic means; and

converting means for performing gamut conversion in performing the emulation using the emulation LUT acquired by the LUT acquiring means.

2. An image processing device according to claim 1 , wherein the generating means generates the emulation LUT using the device-in-use LUT and the target device LUT.

3. An image processing device according to claim 1 , further comprising storing means for storing the emulation LUT, wherein

the acquiring means acquires the emulation LUT from the storing means.

4. An image processing device according to claim 1 , wherein the emulation LUT, the device-in-use LUT and the target device LUT are three-dimensional LUTs.

5. An image processing device according to claim 1 , wherein the device in use and the target device are display devices that apply color conversion processing and display processing to an image signal.

6. An image processing device according to claim 1 , wherein the device in use and the target device are printing devices that apply color conversion processing and print processing to an image signal.

7. An image processing device according to claim 1 , wherein the device in use and the target device are imaging devices that apply recording processing or output processing to an image signal obtained by imaging processing.

8. An image processing method, stored on a tangible computer-readable medium that is executed by a hardware processor, of performing color conversion processing using a lookup table (LUT), comprising the steps of:

acquiring an emulation LUT for applying emulation of a gamut to a target device from a device in use, the emulation LUT being generated using (i) a device-in-use LUT for performing correction corresponding to input and output characteristics of the device in use and (ii) a target device LUT for performing correction corresponding to input and output characteristics of the target device, utilizing a LUT generating device;

updating, for each lattice point forming the target device LUT, a value of the lattice point to a value obtained by gamut-converting the value of the lattice point into a gamut of the device-in-use, utilizing a first LUT arithmetic unit;

updating a value of a lattice point forming the target device LUT updated by the first LUT arithmetic unit to a value of a lattice point forming the device-in-use LUT, utilizing a second LUT arithmetic unit;

finding, from the device-in-use LUT, a lattice point closest to the value of the lattice point forming the target device LUT updated by the first LUT arithmetic unit and updates a value of the lattice point found to the value of the lattice point forming the target device LUT updated by the first LUT arithmetic unit, utilizing the second LUT arithmetic unit; and

performing gamut conversion in performing the emulation using the emulation LUT acquired in the LUT acquiring step, utilizing a gamut converting unit.

9. An image processing device, including a hardware processor, that performs color conversion processing using a lookup table (LUT), comprising:

a LUT generating device acquiring an emulation LUT for applying emulation of a gamut to a target device from a device in use, the emulation LUT being generated using (i) a device-in-use LUT for performing correction corresponding to input and output characteristics of the device in use and (ii) a target device LUT for performing correction corresponding to input and output characteristics of the target device;

wherein the LUT generating device including first LUT arithmetic unit for updating, for each lattice point forming the target device LUT, a value of the lattice point to a value obtained by gamut-converting the value of the lattice point into a gamut of the device-in-use, and second LUT arithmetic etic unit for updating a value of a lattice point forming the target device LUT updated by the first. LUT arithmetic unit to a value of a lattice point forming the device-in-use LUT,

wherein the second LUT arithmetic unit finds, from the device-in-use LUT, a lattice point closest to the value of the lattice point forming the target device LUT updated by the first LUT arithmetic unit and updates a value of the lattice point found to the value of the lattice point forming the target device LUT updated by the first LUT arithmetic unit; and

a gamut converting unit performing gamut conversion in performing the emulation using the emulation LUT acquired by the LUT acquiring unit.