Determining color mappings for a color printer

An apparatus 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 apparatus comprising the following means to determine an entry in the reverse model look-up table for a device independent target color:

• search performing means for performing a binary search of the forward model look-up table to locate a cell that contains the device independent target color;
• interpolating means for interpolating entries from the forward model look-up table at grid points that define the cell so as to obtain device dependent colors corresponding to the device independent target color;
• and
• storing means for storing the device dependent color at the grid point of the reverse model look-up table for the device independent target color.

Computer-executable process steps stored on a computer-readable medium, the computer executable process steps to derive 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 computer-executable process steps comprising the following codes to determine an entry in the reverse model look-up table for a device independent target color:

• code to perform a binary search of the forward model look-up table to locate a cell that contains the device independent target color;
• code to interpolate entries from the forward model look-up table at grid points that define the cell so as to obtain device dependent colors corresponding to the device independent target color;
• and
• code to store the device dependent color at the grid point of the reverse model look-up table for the device independent target color.

A computer-readable medium which stores computer-executable process steps, the computer-executable process steps to derive 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 computer-executable process steps comprising the following steps to determine an entry in the reverse model look-up table for a device independent target color:

• a search performing step to perform a binary search of the forward model look-up table to locate a cell that contains the device independent target color;
• an interpolating step to interpolate entries from the forward model look-up table at grid points that define the cell so as to obtain device dependent colors corresponding to the device independent target color;
• and
• a storing step to store the device dependent color at the grid point of the reverse model look-up table for the device independent target color.

An apparatus 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 apparatus comprising:

• a memory including a region for storing the forward model look-up table, a region for storing the reverse model look-up table, and a region for storing executable process steps;
• and
• a processor for executing the executable process steps;
• wherein the executable process steps include the following steps to determine an entry in the reverse model look-up table for a device independent target color:
• (a) performing a binary search of the forward model look-up table to locate a cell that contains the device independent target color, (b) interpolating entries from the forward model look-up table at grid points that define the cell so as to obtain device dependent colors corresponding to the device independent target color, and (c) storing the device dependent color at the grid point of the reverse model look-up table for the device independent target color.