Method for transforming color signals and apparatus for the method

A color signal transforming apparatus having three input signals representative of colors being each divided into lower bits and higher bits which are combined to form address signals, and said apparatus comprising a color correction memory, when receiving the address signals, for producing basic data, interpolation data generating means for generating combinations of interpolation data in accordance with combinations of the higher bits and the lower bits, and adder means for adding an output signal of the color correction memory and an output signal of the interpolation data generating means, to thereby produce an output signal, wherein said interpolation data generating means includes means for dividing a hexahedron of an object to be interpolated into six tetrahedrons each passing though one of eight lattice points constituting the hexahedron of the interpolated object, and for assigning different combinations of interpolation data to the tetrahedrons in one-to-one correspondence manner, wherein said interpolation data generating means comprises a plurality of comparators for comparing the lower bits of the three input signals, some shifted lower bits of the three input signals, or results of addition/subtraction thereof, and means for producing combinations of output signals of said comparators in the form of a plurality of interpolation region select signals that are fit to a commonness of interpolation sensitivity signals.

A color signal transforming apparatus comprising:

• a start address/lower bit generating memory, when receiving an address signal containing two of three input signals representative of a first colorimetric coordinate, for producing a start address previously set in consideration of a color reproduction range of an output device and the modified lower bits of the two input signals;
• maximum/minimum generating means, when receiving an address signal containing two of the three input signals, for generating the maximum and minimum values of the remaining one input signal in consideration of the color reproduction range of the output device;
• calculating means for modifying the remaining one input signal using the maximum and minimum values output from said maximum/minimum generating means;
• an address adder for adding the start address output from said start address/lower bit generating memory and the higher bit of a fixed number of the remaining one input signal;
• a basic data color correction memory for producing basic data signals representative of colors of a second colorimetric coordinate in response to an address signal as the output signal of said address adder;
• interpolation data generating means for generating a set of interpolation data on the basis of the combination of the higher bits output from said address adder and the combination of the modified lower bits of said input signals;
• adder means for producing output signals representative of colors of the second colorimetric coordinate by adding the output signal of said basic data color correction memory and the output signal of said interpolation data generating means;
• and
• said interpolation data generating means including means for dividing the hexahedron of each object to be interpolated into six tetrahedrons each passing through one of eight lattice points constituting the hexahedron of the interpolated object, and for assigning different sets of interpolation data to the tetrahedrons in one-to-one correspondence manner.