Patent ID: 6870636

Claim:
A method for deriving a reverse model look-up table whose entries represent device dependent colors as a function of device independent colors, based on a forward model look-up table whose entries represent device independent colors obtained in response to printout of corresponding device dependent color components, wherein the forward model and the reverse model look-up tables both comprise a grid of cells in their respective color spaces with entries at each grid point of the grid, the method comprising the following steps to determine an entry in the reverse model look-up table for a device independent target color: performing a binary search of the forward model look-up table to locate a cell that contains the device independent target color, wherein performing a binary search comprises steps of: dividing the device independent color space into multiple regions defined by device independent colors with reference to a starting color in device dependent color space; determining which of the multiple regions contains the device independent target color; updating the starting color value based on which region contains the device independent target color; and iterating the dividing, determining and updating steps until a cell containing the updated starting color and a cell containing a previous starting color are the same; interpolating entries from the forward model look-up table at grid points that define the cell located by the binary search of the forward model look-up table, so as to obtain device dependent colors corresponding to the device independent target color; and storing the device dependent color at the grid point of the reverse model look-up table for the device independent target color.