Claims
- 1. A method for generating a spatial-priority matrix for specifying an order for forming display elements in a stochastic screen for use in displaying a color image in a device, said method comprising:
- receiving a spatial-priority signal representing values of a plurality of elements in a square matrix, said values representing an order of fill in a square stochastic screen,
- receiving an aspect-ratio signal representing one or more ratios of dimensions of output presented by said device,
- forming groups of elements in said spatial-priority matrix, each group corresponding to a respective element in said square matrix and containing a plurality of elements according to said aspect-ratio signal and arranged to have dimensions inversely proportional to said dimensions of output, and
- assigning values to elements in said groups of elements in response to said spatial-priority signal, wherein an element in a respective group of elements is assigned a value according to the value of the element in said square matrix corresponding to said respective group of elements.
- 2. A method according to claim 1 wherein said square matrix is of size N by N and represents an order for adding Y pixels to an area already containing Z pixels, where Z.gtoreq.0, so that the resulting distribution of all X=Y+Z pixels in the area is optimally uniform provided X.ltoreq.N.sup.2, but wherein the distribution of just said Y pixels need not be optimally uniform if Z>0.
- 3. A method according to claim 1 wherein said square matrix contains N.sup.2 elements, each of said groups of elements contains A elements, and said spatial-priority matrix contains A.multidot.N.sup.2 elements, and wherein elements in said respective group of elements are assigned values derived from V+K.multidot.N.sup.2 for values of K ranging from zero to A-1, where V is the value of the element in said square matrix corresponding to said respective group of elements.
- 4. A method according to claim 3 wherein said square matrix is of size N by N and represents an order for adding Y pixels to an area already containing Z pixels, where Z.gtoreq.0, so that the resulting distribution of all X=Y+Z pixels in the area is optimally uniform provided X.ltoreq.N.sup.2, but wherein the distribution of just said Y pixels need not be optimally uniform if Z>0.
- 5. A method according to claim 3 wherein said assigned values are derived by a mapping into a range of an n-bit grayscale.
- 6. A method according to claim 5 wherein said square matrix is of size N by N and represents an order for adding Y pixels to an area already containing Z pixels, where Z.gtoreq.0, so that the resulting distribution of all X=Y+Z pixels in the area is optimally uniform provided X.ltoreq.N.sup.2, but wherein the distribution of just said Y pixels need not be optimally uniform if Z>0.
- 7. An apparatus for generating a spatial-priority matrix for specifying an order for forming display elements in a stochastic screen for use in displaying a color image in a device, said apparatus comprising:
- means for receiving a spatial-priority signal representing values of a plurality of elements in a square matrix, said values representing an order of fill in a square stochastic screen,
- means for receiving an aspect-ratio signal representing one or more ratios of dimensions of output presented by said device,
- means for forming groups of elements in said spatial-priority matrix, each group corresponding to a respective element in said square matrix and containing a plurality of elements according to said aspect-ratio signal and arranged to have dimensions inversely proportional to said dimensions of output, and
- means for assigning values to elements in said groups of elements in response to said spatial-priority signal, wherein an element in a respective group of elements is assigned a value according to the value of the element in said square matrix corresponding to said respective group of elements.
- 8. An apparatus according to claim 7 wherein said square matrix is of size N by N and represents an order for adding Y pixels to an area already containing Z pixels, where Z.gtoreq.0, so that the resulting distribution of all X=Y+Z pixels in the area is optimally uniform provided X.ltoreq.N.sup.2, but wherein the distribution of just said Y pixels need not be optimally uniform if Z>0.
- 9. An apparatus according to claim 7 wherein said square matrix contains N.sup.2 elements, each of said groups of elements contains A elements, and said spatial-priority matrix contains A.multidot.N.sup.2 elements, and wherein elements in said respective group of elements are assigned values derived from V+K.multidot.N.sup.2 for values of K ranging from zero to A-1, where V is the value of the element in said square matrix corresponding to said respective group of elements.
- 10. An apparatus according to claim 9 wherein said square matrix is of size N by N and represents an order for adding Y pixels to an area already containing Z pixels, where Z.gtoreq.0, so that the resulting distribution of all X=Y+Z pixels in the area is optimally uniform provided X.ltoreq.N.sup.2, but wherein the distribution of just said Y pixels need not be optimally uniform if Z>0.
- 11. An apparatus according to claim 9 wherein said assigned values are derived by a mapping into a range of an n-bit grayscale.
- 12. An apparatus according to claim 11 wherein said square matrix is of size N by N and represents an order for adding Y pixels to an area already containing Z pixels, where Z.gtoreq.0, so that the resulting distribution of all X=Y+Z pixels in the area is optimally uniform provided X.ltoreq.N.sup.2, but wherein the distribution of just said Y pixels need not be optimally uniform if Z>0.
- 13. A medium readable by a machine embodying a program of instructions for execution by said machine to perform a method for generating a spatial-priority matrix for specifying an order for forming display elements in a stochastic screen for use in displaying a color image in a device, said method comprising:
- receiving a spatial-priority signal representing values of a plurality of elements in a square matrix, said values representing an order of fill in a square stochastic screen,
- receiving an aspect-ratio signal representing one or more ratios of dimensions of output presented by said device,
- forming groups of elements in said spatial-priority matrix, each group corresponding to a respective element in said square matrix and containing a plurality of elements according to said aspect-ratio signal and arranged to have dimensions inversely proportional to said dimensions of output, and
- assigning values to elements in said groups of elements in response to said spatial-priority signal, wherein an element in a respective group of elements is assigned a value according to the value of the element in said square matrix corresponding to said respective group of elements.
- 14. A medium according to claim 13 wherein said square matrix is of size N by N and represents an order for adding Y pixels to an area already containing Z pixels, where Z.gtoreq.0, so that the resulting distribution of all X=Y+Z pixels in the area is optimally uniform provided X.ltoreq.N.sup.2, but wherein the distribution of just said Y pixels need not be optimally uniform if Z>0.
- 15. A medium according to claim 13 wherein said square matrix contains N.sup.2 elements, each of said groups of elements contains A elements, and said spatial-priority matrix contains A.multidot.N.sup.2 elements, and wherein elements in said respective group of elements are assigned values derived from V+K.multidot.N.sup.2 for values of K ranging from zero to A-1, where Vis the value of the element in said square matrix corresponding to said respective group of elements.
- 16. A medium according to claim 15 wherein said square matrix is of size N by N and represents an order for adding Y pixels to an area already containing Z pixels, where Z.gtoreq.0, so that the resulting distribution of all X=Y+Z pixels in the area is optimally uniform provided X.ltoreq.N.sup.2, but wherein the distribution of just said Y pixels need not be optimally uniform if Z>0.
- 17. A medium according to claim 15 wherein said assigned values are derived by a mapping into a range of an n-bit grayscale.
- 18. A medium according to claim 17 wherein said square matrix is of size N by N and represents an order for adding Y pixels to an area already containing Z pixels, where Z.gtoreq.0, so that the resulting distribution of all X=Y+Z pixels in the area is optimally uniform provided X.ltoreq.N.sup.2, but wherein the distribution of just said Y pixels need not be optimally uniform if Z>0.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of priority of provisional application Ser. No. 60/028,615 filed Aug. 15, 1996 and provisional application Ser. No. 60/034,263 filed Dec. 20, 1996.
US Referenced Citations (17)