Abstract: A test patch generator for electrophotographic machines automatically adjusts test patch exposure to predetermined values regardless of operator-initiated changes in exposure settings. A main illumination source exposes an original document. Integrating the main illumination source produces an electrical signal representative of the amount of such exposure. The signal is modified by a factor selected in accordance with the exposure setting, and the modified signal is used to produce a latent image test patch on a photoconductor member, the patch having an exposure value corresponding to the modified signal. Once the patch is toned, a sensor can be used to measure the patch density and any necessary adjustments to the process parameters made.