Dual registration and process control toned patches

A method and apparatus saves on toner cost and improves productivity for running registration and color process controls in a printer by making dual use of patches for both functions. That is, the small patches normally used only for registration measurement are also used for xerographic process control measurements, thereby eliminating the need for large patches and obtaining registration information and color control information at the same time. The dual use of small patches to measures both registration and color process control is made possible by periodically establishing correlation between the density of large density patches and the smaller registration patches.