Determining cumulative probability values for subsets of elements

A print data processing apparatus comprising:

• a processor;
• a memory storing instructions executable by the processor to:
• acquire a first halftone matrix comprising first threshold values respectively associated with print addressable locations;
• acquire a second halftone matrix comprising second threshold values respectively associated with the print addressable locations;
• acquire data representing an article to be printed and comprising an element set associated with each print addressable location, the element set associated with each print addressable location comprising a first subset of elements and a second subset of elements, each element identifying a print material selection and a probability that the print material selection identified is to be applied to the print addressable location;
• determine a first set of cumulative probability values spanning a first value range and associated with the elements of the first subset associated with each print addressable location by, for each element, summing the probability of the element and the probabilities of all preceding elements in the first subset to obtain a cumulative probability associated with the element;
• determine a second set of cumulative probability values spanning a second value range and associated with the elements of the second subset associated with each print addressable location by, for each element, summing the probability of the element and the probabilities of all preceding elements in the second subset to obtain a cumulative probability associated with the element;
• and
• apply the halftone matrix to the data representing the article to be printed to identify for each print addressable location:
• each element of the first subset associated with the print addressable location for which the associated cumulative probability value of the first set is greater than the first threshold value associated with the print addressable location;
• and
• each element of the second subset associated with the print addressable for which the associated cumulative probability value is greater than the second threshold value associated with the print addressable location.

A non-transitory machine-readable medium with instructions stored thereon and that are executable by a processor to:

• acquire a first halftone matrix comprising a first threshold value associated with a print addressable location and having a first bit depth;
• acquire a second halftone matrix comprising a second threshold value associated with the print addressable location and having a second bit depth;
• acquire data representing an article to be printed and comprising a first element subset and a second element subset that each comprise a plurality of elements, each element identifying a print material selection and a probability that the print material selection is to be applied to the print addressable location;
• determine a first set of cumulative probability values associated with the elements of the first element subset and spanning a first value range;
• determine a second set of cumulative probability values associated with the elements of the second element subset and spanning a second value range;
• compare the first set to a first set of bits of the first threshold value, the first set of bits having a number of bits related to the first value range;
• compare the second set to a second set of bits of the second threshold value, the second set of bits having a number of bits related to the second value range;
• select for the print addressable location each element in the first halftone matrix for which the associated cumulative probability value of the first set is greater than the first set of bits;
• and
• selecting for the print addressable location each element in the second halftone matrix for which the associated cumulative probability value of the second set is greater than the second set of bits.