Patent ID: 7013096

Claim:
An image forming apparatus, comprising: an image bearing member on which a latent image corresponding to image information is formed; developing means for developing the latent image formed on said image bearing member with a developer including a carrier and a toner; supplying means for supplying the toner to said developing means; detecting means for detecting a magnetic permeability of the developer; counting means for counting pixel information corresponding to the image information; and selecting means for selecting between a first mode in which an amount of the toner supplied from said supplying means to said developing means is controlled on the basis of an output from said detecting means and a second mode in which the amount of the toner supplied from said supplying means to said developing means is controlled on the basis of an output from said counting means, wherein said selecting means selects between the first mode and the second mode in accordance with a difference value between a value detected by said detecting means before a stop of an image forming operation and a value detected by said detecting means after a start of an image forming operation after the stop of the image formation operation.