Method and a device for converting a color coordinate set

Claim 1

A method for converting a color defined in a first n-dimensional device dependent color space to a corresponding color defined in a second m-dimensional (m≧n; n≧p; m>p; p≧3) device dependent color space, wherein said color is first converted from said first device dependent color space to a first device independent color space and thereafter from said first device independent color space to a second device independent color space in order to be there after converted to said second device dependent color space, and wherein for each conversion from one color space to another there is determined a respective mapping algorithm mapping a color coordinate set from said one color space to said other color space, and wherein each device dependent color space comprises a color gamut and said color gamut of said first respectively second device dependent color space is each time by means of said respective mapping algorithm mapped to said first respectively second device independent color space in order to each time define therein a first respectively a second color gamut which is correlated with said first respectively said second device dependent color space and subsequently there being verified if said color coordinate set converted from said first to said second device independent color space is within said correlated color gamut defined within said second device independent color space, and wherein for each (m-p) th color dimension from said second device dependent color space there is each time defined a color value and said color coordinate set of said second device dependent color space is determined on the basis of said color value, which color value defines a further color gamut within said color gamut of said second device dependent color space, which further color gamut is mapped by means of said respective mapping to said second device independent color space in order to define therein a third color gamut and if by said verifying there is established that said converted color coordinate set is outside said third but inside respectively outside said correlated second color gamut that color coordinate set is substituted by a first respectively a second color coordinate set.

Claim 2

A method for converting a color defined in a first n-dimensional device dependent color space to a corresponding color defined in a second m-dimensional (m≧n; n≧p; m>p; p≧3) device dependent color space, wherein said color is first converted from said first device dependent color space to a first device independent color space and thereafter from said first device independent color space to a second device independent color space in order to be there after converted to said second device dependent color space, and wherein for each conversion from one color space to another there is determined a respective mapping algorithm mapping a color coordinate set from said one color space to said other color space, and wherein each device dependent color space comprises a color gamut and said color gamut of said first respectively second device dependent color space is each time by means of said respective mapping algorithm mapped to said first respectively second device independent color space in order to each time define therein a first respectively a second color gamut which is correlated with said first respectively said second device dependent color space and subsequently there being verified if said color coordinate set converted from said first to said second device independent color space is within said correlated color gamut defined within said second device independent color space, and wherein for each (m-p) th color dimension from said second device dependent color space there is each time defined a color value and said color coordinate set of said second device dependent color space is determined on the basis of said color value, which color value defines a further color gamut within said color gamut of said second device dependent color space, which further color gamut is mapped by means of said respective mapping to said second device independent color space in order to define therein a third color gamut and if by said verifying there is established that said converted color coordinate set is outside said third but inside respectively outside said correlated second color gamut that color coordinate set is substituted by a first respectively a second color coordinate set.

Claim 17

A method as claimed in anyone of the claims 13, 14 or 15, wherein for each first color coordinate set to be converted a subspace wherein said first color coordinate set is located, is identified and wherein for said interpolation use is made of said second color coordinates of said corner points of said identified subspace which second color coordinates are stored in said memory.

Claim 18

A method as claimed in anyone of the claims 13, 14, or 15 wherein for each first color coordinate set to be converted a subspace wherein said first color coordinate set is located, is identified and wherein for said interpolation use is made of said second color coordinates of said corner points of said identified subspace which second color coordinates are stored in said memory and wherein for said identifying of said subspace use is made of most significant bits of said color coordinate set to be converted in order to determine a first corner point of said subspace to be identified and wherein remaining corner points of the subspace to be identified are identified by incrementation of said most significant bits.

Claim 21

A method as claimed in anyone of the claims 13, 14 or 15 wherein for each first color coordinate set to be converted a subspace wherein said first color coordinate set is located, is identified and wherein for said interpolation use is made of said second color coordinates of said corner points of said identified subspace which second color coordinates are stored in said memory and wherein for said identifying of said subspace use is made of most significant bits of said color coordinate set to be converted in order to determine a first corner point of said subspace to be identified and wherein remaining corner points of the subspace to be identified are identified by incrementation of said most significant bits and wherein on the basis of said most significant bit addresses are formed for addressing said memory.

Claim 22

A method as claimed in anyone of the claims 13, 14, 15, wherein for each first color coordinate set to be converted a subspace wherein said first color coordinate set is located, is identified and wherein for said interpolation use is made of said second color coordinates of said corner points of said identified subspace which second color coordinates are stored in said memory and wherein on the basis of least significant bits of said color coordinate set to be converted weight coefficients are selected which represent a contribution of said color coordinate set to each second color coordinates which are related to said corner points of said identified subspace.

Claim 23

A method as claimed in anyone of the claims 13, 14 or 15 wherein for each first color coordinate set to be converted a subspace wherein said first color coordinate set is located, is identified and wherein for said interpolation use is made of said second color coordinates of said corner points of said identified subspace which second color coordinates are stored in said memory and wherein for said identifying of said subspace use is made of most significant bits of said color coordinate set to be converted in order to determine a first corner point of said subspace to be identified and wherein remaining points of the subspace to be identified are identified by incrementation of said most significant bits and wherein on the basis of said most significant bit addresses are formed for addressing said memory and wherein on the basis of least significant bits of said coordinate set to be converted weight coefficients are selected which represent a contribution of said color coordinate set to each second color coordinates which are related to said corner points of said identified subspace and wherein said interpolation is realized on the basis of said second color coordinate set and said weight coefficients.

Claim 27

A device as claimed in any one of the claims 23, 24 or 25, wherein said substitution means are provided for generating said first color coordinate set by determining a difference between said color coordinate set obtained by mapping to said second device independent color space and a further color coordinate set in said second device independent color space obtained by using said color value and by means of thereafter minimizing said difference.