In predicting a quantity of a printing product necessary for printing a document,
the document is stored in its entirety as digital data. Each page of the document
is divided into bands of the digital data. From the digital data, a table of limited
capacity is created, which describes at least part of a monochromatic component
of one of the bands, with the monochromatic component corresponding to the printing
product and each cell of the table representing at least a pixel. A number of switched-on
pixels in the table is counted, with a switched-on pixel corresponding to a pixel
for which a portion of the printing product must be ejected. Before enabling or
demanding printing, a necessary quantity of the printing product is derived from
a number of switched-on pixels corresponding to each band.
