Dithered quantization using neighborhood mask array to approximate interpolate

In an image forming system that has access to a sparse lookup table having lattice points that convert color image data from a first color space to a second color space, a method for converting samples of the color image data from the first color space to the second color space by approximating, over a neighborhood of samples, a result that would be obtained using linear interpolation, comprising the acts of:

• obtaining a sample of the image data having bits representing color components;
• for each color component of the image data:
• quantizing the bits representing the particular color component by truncating one or more masked bits, such that one or more most significant index bits remain, the index bits having a sufficient number of bits for indexing the sparse lookup table;
• comparing the one or more masked bits with a corresponding entry in a mask array to determine whether the value of a specific one of the masked bits indicates that the index bits are to be incremented prior to being used for indexing the lookup table;
• if the act of comparing indicates that the index bits are to be incremented, then incrementing the index bits, otherwise not incrementing the index bits;
• then
• using the index bits for each of the color components as an indices to the lookup table;
• and
• obtaining values for the sample expressed in the second color space from a lattice point of the sparse lookup table indexed by the index bits.

An image forming system for converting samples of image data from a first color space to a second color space by referencing a sparse lookup table and approximating the results that would be obtained using linear interpolation with the sparse lookup table, the image forming system comprising:

• a processor;
• and
• a computer-readable medium operatively coupled with the processor having stored thereon:
• the sparse lookup table;
• and
• executable instructions that, when executed by the processor, cause the image forming system to perform the acts of:
• quantizing a sample of image data by truncating from the sample one or more masked bits, such that one or more most significant index bits remain, the index bits having a sufficient number of bits for indexing the sparse lookup table;
• comparing the one or more masked bits with a corresponding entry in a mask array to determine whether the value of a specific one of the masked bits indicates that the index bits are to be incremented prior to being used for indexing the lookup table;
• if the act of comparing indicates that the index bits are to be incremented, then incrementing the index bits, otherwise not incrementing the index bits;
• and then
• using the index bits as an index to the lookup table to obtain the value of the sample expressed in the second color space.

A computer-readable medium, for converting samples of input data to output data in a system using a sparse lookup table by approximating, over a neighborhood of samples, a result that would be obtained using linear interpolation, the computer readable medium comprising:

• executable instructions, that when executed in the system, cause the system to perform the acts of:
• quantizing sample of image data obtained by the image forming system by truncating from the sample one or more masked bits, such that one or more most significant index bits remain, the index bits having a sufficient number of bits for indexing the sparse lookup table;
• comparing the one or more masked bits with a corresponding entry in a mask array to determine whether the value of a specific one of the masked bits indicates that the index bits are to be incremented prior to being used for indexing the lookup table;
• if the act of comparing indicates that the index bits are to be incremented, then incrementing the index bits, otherwise not incrementing the index bits;
• and then
• using the index bits as an index to the lookup table.