Identification of faulty jets via sensing on customer images

A method of monitoring jets of a color imaging device, the jets respectively outputting inks of different colors, the imaging device including a multichromatic sensor that senses images output by the imaging device, the method comprising:

• generating a correspondence map between an output color space of the jets and an output color space of the multichromatic sensor;
• measuring actual color values of an image output by the imaging device at multiple locations, the image generated from actual image data;
• calculating predicted color values of the multichromatic sensor for each of the multiple locations, the predicted color values for each of the multiple locations including predicted color values for multiple different possible operating configurations of the jets, wherein each jet can have an operating state of (i) properly operating or (ii) faulty, the different operating configurations comprising different combinations of properly operating and faulty jets for a predetermined group of the jets, each jet of the predetermined group outputting a different one of the different colors;
• and
• determining whether the jets are (i) operating properly or (ii) faulty, by comparing the measured actual color values of the multiple locations with the corresponding predicted color values for each of the multiple locations.

A system for monitoring jets in a color imaging device, the jets each corresponding to different ones of a plurality of colors of the color imaging device, the system comprising:

• a sensor that senses images and outputs actual gray scale values;
• a memory storing a correspondence map between an output color space of the jets and an output gray scale space of the sensor;
• a processing device comprising:
• a sensor controlling unit that controls the sensor to measure printed output of the color imaging device at multiple locations in the printed output and to output corresponding actual gray scale values,
• a prediction unit that calculates predicted gray scale values of the sensor for each of the multiple locations, the predicted gray scale values for each of the multiple locations including predicted gray scale values for multiple possible operating state configurations of the jets wherein each jet can independently have the operating states of properly operating and faulty, and
• a judgment unit that determines, for a predetermined group of jets having jets each of which corresponds to a different one of the plurality of colors, the operating states of the jets based on the predicted gray scale values and the actual gray scale values for the multiple locations.