Patent ID: 7956823

Claim:
A color display device that determines a relationship between three color components of an input color image signal in terms of gradation levels of the three color components of an input color image signal, and that carries out a different calculation for each input color image signal depending on which of six patterns of the relationship that the input color image signal belongs to, the calculation being performed for each of the three color components excluding a component with a relatively smallest gradation level, using variables varying depending on the relationship among the respective gradation levels of the three color components, wherein the gradation level of the color component with the relatively smallest gradation level remains unchanged before and after the calculation, and wherein: the input color image signal is converted into an output color image signal with the at least three color components respectively having gradation levels of r′, g′and b′, which are given by: r′=r+ro+yo+mo, g′=g+go+yo+co, b′=b+bo+mo+co, where r, g and b are values obtained by dividing original gradation levels of the three color components of the input color image signal by a maximum gradation value N−1; and in a case [1] where r≧g≧b: ro=Krg ( r−g ) Nr , yo=Kyg ( g−b ) Ny , go=bo=mo=co=0, in a case [2] where r≧b>g: ro=Krb ( r−b ) Nr , mo=Kmb ( b−g ) Nm , go=bo=yo=co=0, in a case [3] where b>r≧g: bo=Kbr ( b−r ) Nb , mo=Kmr ( r−g ) Nm , ro=go=yo=co=0, in a case [4] where b>g>r: bo=Kbg ( b−g ) Nb , co=Kcg ( g−r ) Nc , ro=go=yo=mo=0, in a case [5] where g≧b>r: go=Kgb ( g−b ) Ng , co=Kcb ( b−r ) Nc , ro=bo=yo=mo=0, in a case [6] where g>r≧b: go=Kgr ( g−r ) Ng , yo=Kyr ( r−b ) Ny , ro=bo=mo=co=0, in which Krg, Krb, Kbr, Kbg, Kgb, Kgr, Kyg, Kyr, Kmb, Kmr, Kcg and Kcb are variables which change depending on values of r, g and b; and Nr, Ng, Nb, Ny, Nm and Nc are constants not less than 0.