1. In an electrographic machine for reproducing originals and having (1) means for substantially uniformly charging a recording member, (2) means for imagewise exposing the charged recording member at a nominal exposure level to produce a latent charge image (3) developing means, including an electrode, for depositing toner on the latent charge image, and (4) means for electrically biasing the electrode at a nominal bias voltage level; the improvement comprising: means for producing a signal having a value characteristic of the exposure level associated with a latent charge image; means, operatively coupled to said signal producing means for storing the produced signal value and the nominal bias voltage level which cooperate to produce a first reproduction of an original, said first reproduction having a desired quality; means for producing a comparison signal by comparing the signal value of the sensed exposure level associated with a subsequent latent charge image with the corresponding stored signal value for the corresponding latent charge image of the same original; and means responsive to said comparison signal for varying the bias voltage level associated with the latent charge image to thereby produce a developed image having substantially the same reproduction quality as that produced by the stored signal values.