Patent ID: 7944584
Filing Date: 2011-05-17
Classification: H04N

Abstract:
1. A color-converting device for converting an input color signal defined in an input-side color space into an output color signal defined in an output-side color space, the color-converting device comprising: an input portion that receives an input color signal defined in an input-side color space, the input color signal having a plurality of input-side color components, the input-side color space having a plurality of coordinate axes defined by the plurality of input-side color components, the input-side color space having a predetermined gray axis, each position on the gray axis having values equal to one another for the plurality of input-side color components; a storing portion prestored with a color conversion table indicative of a one-to-one correspondence between a plurality of input-side grid color signals defined in the input-side color space and a plurality of output-side color signals defined in an output-side color space, each input-side grid color signal having the plurality of input-side color components, the plurality of input-side grid color signals indicating a plurality of grid points, each of which is defined by the plurality of coordinate axes in the input-side color space, each output-side color signal having a plurality of output-side color components; a cube-employing interpolation portion that is configured so as to be capable of selecting, from among all the grid points, eight grid points forming a cube, which includes therein a position of the input color signal defined in the input-side color space, and performing an interpolation calculation to convert the input color signal into an output color signal based on eight output-side color signals for the eight grid points and based on the positions of the eight grid points in relation to the position of the input color signal; a gray-axis-solid-employing interpolation portion that is configured so as to be capable of selecting, from among all the grid points, several grid points forming a solid, which includes therein a position of the input color signal defined in the input-side color space and whose one edge extends in a direction in which the gray axis extends, and performing an interpolation calculation to convert the input color signal into an output color signal based on several output-side color signals for the several grid points and based on the positions of the several grid points in relation to the position of the input color signal; a determining portion that checks the color conversion table; and a selection portion that selects either one of the cube-employing interpolation portion and the gray-axis-solid-employing interpolation portion dependently on the determined results, and that causes the selected one of the cube-employing interpolation portion and the gray-axis-solid-employing interpolation portion to execute its interpolation operation to convert the input color signal into an output color signal, wherein the determining portion includes a homogeneous determination portion that determines whether or not there exists in the color conversion table at least one homogeneous grid point that is surrounded by a plurality of surrounding grid points, a difference, in each output-side color component, between an output-side color signal for the homogeneous grid point and an output-side color signal for each surrounding grid point being less than or equal to a predetermined threshold value; and wherein the selection portion selects the cube-employing interpolation portion when the homogeneous determination portion determines that there exists at least one homogeneous grid point in the color conversion table, and selects the gray-axis-solid-employing interpolation portion when the homogeneous determination portion determines that there exists no homogeneous grid point in the color conversion table, wherein the homogeneous determination portion includes: