Patent ID: 7394470

Claim:
A computer-implemented method for reversibly converting a data format as part of a coding and decoding process that includes compression, the computer-implemented method comprising: performing a forward transformation and performing a backward transformation reciprocally on data being transformed between unit systems having different resolution levels defined by a brightness and a color difference, the forward transformation being performed prior to performing the compression, wherein in the forward transformation and the backward transformation, a first unit system having a lower resolution level is used as a common unit system, and the method further comprising performing a reversible data conversion with use of an integer operation for data in the first unit system and data in a second unit system having a higher resolution level higher than the first unit system, wherein the first unit system is for a first color space and the second unit system is for a second color space that is based on three primary colors of lights, the first color space being different than the second color space and the second color space having the higher resolution level, and further wherein performing the reversible data conversion comprises determining each component value of one of the first and second color spaces during data conversion in at least one of the forward and backward transformations based on all of the component values of the other of the first and second color spaces, and by using the first color space as the common unit system, the reversible data conversion is performed by the integer operation, so that the backward transformation to transform first data in the first color space to second data in the second color space and the forward transformation to transform the second data in the second color space to third data in the first color space are conducted, where the first data corresponds to the third data.