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US 5,689,349 AGranted
Method and a device for generating printing data in a color space defined for non-standard printing inks
AssigneeBarco Graphics N.V.
InventorsLieven Plettinck, Jean-Pierre Van De Capelle
Life of this patent
Estimating the term…
Abstract
A method and a device for generating printing data wherein a first color separation defined in a first device dependent color space of standard printing inks is converted into a second color separation defined in a second device dependent color space of non-standard printing inks. The conversion is realized by means of a conversion matrix which is multiplied with the first color separation
Claims16
A method for generating printing data for a picture to be printed, said picture being comprised of pixels, said method comprising:
- defining a first n-dimensional device dependent colour space in which colour contributions expressed in terms of coordinates in said first colour space correspond to those of n colours of standard printing inks;
- determining within said first colour space a first colour coordinate for each of said pixels of said picture;
- defining a second m-dimensional device dependent colour space in which colour contributions expressed in terms of coordinates in said second colour space correspond to those of m colours of non-standard printing inks, said second colour space having a colour gamut;
- selecting a set of p (p.gtoreq.n) different colours among said colour gamut of said second colour space, each of said p colours being separated by at least a predetermined colour distance from each other;
- determining a first colour table representing, for each colour of said selected set of p different colours, colour contributions expressed in terms of coordinates in said first colour space;
- determining a second colour table representing, for each colour of said selected set of p different colours, colour contributions expressed in terms of coordinates in said second colour space;
- forming a first p by p matrix having as a p.sub.ij.sup.th (1.ltoreq.i.ltoreq.p;
- 1.ltoreq.j.ltoreq.p) matrix coefficient a j.sup.th colour coordinate of an i.sup.th colour within said first table;
- forming a second m by p matrix by first inverting said first matrix and by forming m third p by 1 matrices, each of said third matrices having as coefficients a respective q.sup.th (1.ltoreq.q.ltoreq.m) one of said colour coordinates in said second colour space of each of said colours belonging to said selected set of p different colours, said second matrix having as q.sub.th (1.ltoreq.q.ltoreq.m) row coefficients the transposed result of multiplying said inverted first matrix with a respective one of said third matrices;
- and
- determining a second colour coordinate within said second colour space for each of said pixels of said picture by multiplying said second matrix by said first colour coordinate.
8 more elements
A device for generating printing data for a picture to be printed, said picture being comprised of pixels, said device comprising:
- means for defining a first n-dimensional device dependent colour space in which colour contributions expressed in terms of coordinates in said first colour space correspond to those of n colours of standard printing inks;
- means for determining within said first colour space a first colour coordinate for each of said pixels of said picture;
- means for defining a second m-dimensional device dependent colour space in which colour contributions expressed in terms of coordinates in said second colour space correspond to those of m colours of non-standard printing inks, said second colour space having a colour gamut;
- means for selecting a set of p (p.gtoreq.n) different colours among said colour gamut of said second colour space, each of said p colours being separated by at least a predetermined colour distance from each other;
- means for determining a first colour table representing, for each colour of said selected set of p different colours, colour contributions expressed in terms of coordinates in said first colour space;
- means for determining a second colour table representing, for each colour of said selected set of p different colours, colour contributions expressed in terms of coordinates in said second colour space;
- means for forming a first p by p matrix having as a p.sub.ij.sup.th (1.ltoreq.i.ltoreq.p;
- 1.ltoreq.j.ltoreq.p) matrix coefficient a j.sup.th colour coordinate of an i.sup.th colour within said first table;
- means for forming a second m by p matrix by first inverting said first matrix and by forming m third p by 1 matrices, each of said third matrices having as coefficients a respective q.sup.th (1.ltoreq.q.ltoreq.m) one of said colour coordinates in said second colour space of each of said colours belonging to said selected set of p different colours, said second matrix having as q.sup.th (1.ltoreq.q.ltoreq.m) row coefficients the transposed result of multiplying said inverted first matrix with a respective one of said third matrices;
- and
- means for determining a second colour coordinate within said second colour space for each of said pixels of said picture by multiplying said second matrix by said first colour coordinate.
8 more elements
Dependencies are inferred from the claim text.