Print pattern and algorithm for automatic ink mix detection

A printing device comprising

• a printhead assembly or a printbar including at least one printhead having a printhead die and at least one nozzle,
• a scanning device, and
• a controller,
• wherein the controller is to detect printing fluid mixing contamination of a printhead of the printing device, wherein a test pattern is printed for at least one printing fluid with the printhead, said test pattern is scanned using the scanning device to obtain colorimetric data, metric values are determined from the colorimetric data and a statistical analysis is performed on the metric values in relation to metric values without printing fluid mixing contamination to determine whether any printing fluid mixing contamination has occurred and where any printing fluid mixing contamination has occurred.

A non-transitory computer readable medium encoded with instructions that, when executed by a processor, cause the processor to perform processing comprising:

• printing a test pattern for at least one printing fluid with a printing device;
• scanning the test pattern for the at least one printing fluid with a scanning device;
• obtaining colorimetric data of the test pattern for the at least one printing fluid;
• determining metric values from the colorimetric data;
• performing a statistical analysis on the determined metric values in relation to metric values without printing fluid mixing contamination;
• determining, based on the statistical analysis, whether any printing fluid mixing contamination has occurred;
• and
• determining, based on the statistical analysis, where any printing fluid mixing contamination has occurred.