Color correcting method and apparatus

Claim 2

A color correcting method in a system for printing an image of an object on the basis of a color separation value of the image of the object under a given illuminant, the method comprising the steps of: converting a color separation value to be supplied to a system for printing an image of an object into an intermediate colorimetric system value of one of a spectral reflectance and a spectral transmittance; calculating an estimation value of a colorimetric value of the object under a reference illuminant in accordance with the intermediate colorimetric system value and a spectral distribution of the reference illuminant; and optimizing the color separation value in accordance with the estimation value of the colorimetric value and a colorimetric value of an image of the object under a given illuminant.

Claim 3

A method according to claim 1, wherein the optimizing step comprises a substep of optimizing the color separation value so that one of a square error and an average color difference between the estimation value of the colorimetric value and the colorimetric value of the object under the given illuminant becomes minimum.

Claim 4

A method according to claim 1, wherein the predetermined colorimetric values are colorimetric values of the reproduction target under the desired illuminant.

Claim 5

A method according to claim 1, wherein the color separation value is a set of R (red), G (green), and B (blue).

Claim 6

A method according to claim 1, wherein the color separation value is one of a set and a set of C, M, Y, and K (black).

Claim 7

A method according to claim 1, in which said converting step uses a neural network which has been trained for conversion from the color separation value to the intermediate colorimetric value.

Claim 8

A method according to claim 6, wherein the neural network is a multi-layered feedforward neural network.

Claim 9

A method according to claim 1, wherein the optimizing step comprises performing nonlinear optimization.

Claim 10

A method according to claim 1, wherein the reference illuminant is one illuminant selected from the group consisting of an A illuminant, a B illuminant, a C illuminant, a D illuminant having an arbitrary color temperature, and F1 to F2 illuminants, all of which are defined by the CIE (Commission Internationale de I'Eclairage).

Claim 11

A color correcting apparatus comprising: an image input unit for imaging an object under a given illuminant, the object being printed by a given printing device to generate a color separation value; first conversion means, having a first neural network, for converting the color separation value; first conversion means, having a first neural network, for converting the color separation value into an intermediate colorimetric system value being one of a spectral reflectance and a spectral transmittance; means for obtaining an estimation value of the colorimetric value of the object under a reference illuminant in accordance with the intermediate colorimetric system value and a spectral distribution of the reference illuminant; and optimization means for optimizing the color separation value so that at least one of a square error and an average color difference between the estimation value of the colorimetric value and a colorimetric value of an object under the given illuminant becomes minimum.

Claim 12

A color correcting apparatus comprising: an image input unit for imaging an object under a given illuminant, the object being printed by a given printing device to generate a color separation value; first conversion means, having a first neural network, for converting the color separation value; first conversion means, having a first neural network, for converting the color separation value into an intermediate colorimetric system value being one of a spectral reflectance and a spectral transmittance; means for obtaining an estimation value of the colorimetric value of the object under a reference illuminant in accordance with the intermediate colorimetric system value and a spectral distribution of the reference illuminant; and optimization means for optimizing the color separation value so that at least one of a square error and an average color difference between the estimation value of the colorimetric value and a colorimetric value of an object under the given illuminant becomes minimum.

Claim 13

A color correcting apparatus according to claim 10, in which the optimizing means comprises: second conversion means having a second neural network, for converting the color separation value into the intermediate colorimetric system value of the object under the given illuminant.