In a system including a plurality of elements, or plurality of subsystems
of elements, each performing a process using process control to maintain
operation within a latitude of a setpoint and having an output
characteristic that contributes to an overall output quality
specification of the system, a control method includes setting a desired
overall output quality specification, and determining optimum setpoints
and latitudes of the plurality of elements, within a range of possible
setpoints and latitudes for each element, to achieve the desired overall
output quality specification. The control method further includes
dynamically re-setting the setpoints and/or re-allocating the latitudes
of at least two of the plurality of elements (or subsystems of elements)
to compensate for degradation of the attribute caused by variation in the
output characteristic of one element within the desired overall output
quality specification. The system may be an image forming apparatus, such
as a xerographic system, or a modular document processing system. The
control method may be stored on a computer readable media.