Color calibration in a printing system

A print system comprising:

• a printing device to apply print material to a print medium in a printing process;
• a memory arranged to store computer-readable instructions;
• and
• a processor configured to execute the computer-readable instructions to:
• retrieve a lookup table, LUT, comprising a mapping of first color space to Neugebauer Primary area coverage, NPac, vectors in a second color space, wherein each NPac vector comprises at least one Neugebauer Primary, NP;
• change each NPac vector by modifying the respective at least one NP, wherein the modifying is determined independently from modifications to other NPac vectors and is based on a relative characteristic between the at least one NP and the NPac;
• generate an updated LUT comprising each changed NPac vector;
• and
• provide the updated LUT to the printing device such that the print material is applied in accordance with the updated LUT to print the image on the print medium.

A computer readable medium comprising a set of instructions, that, when executed by a processor of a printing system cause the processor to:

• obtain a lookup table, LUT, that maps input first color space values to Neugebauer Primary area coverage, NPac, vectors in a second color space, wherein each NPac vector comprises at least one Neugebauer Primary, NP and the NPac vectors form the basis of a printing instruction for the image;
• adjust each NPac vector of the LUT based on a characteristic of the corresponding at least one NP relative to that of the NPac vector, such that the modification of each NPac vector is specific to the NPac vector;
• update the LUT with the adjusted NPac vectors;
• and
• change the printing instruction for the image based on the updated LUT.