Pixel binning is a well-known method to reduce the storage capacity of digital images. There remains the question, however, whether binned images obtain an increase of signal or signal-to-noise ratio. Experiments with photographs of point light sources and extended light sources are presented to demonstrate (a) the effect of increase of signal an d (b) the success of pixel binning. The work presen ts a method to compute the signal-to-noise ratio for the binning task. On-chip binning is provided by some hardware devices. On-chip binning will introduce a certain complexity to the calibration of the device and to the derivation of errors obtained from photo metry. Electronic imaging and photography are based on physical constraints. It is shown, that binning does not violate the physical law of conservation o f energy. Binning will provide averaged pixels at lowe red dimension and resolution of the image. Binning does not improve the signal-to-noise ratio or the susceptibility of the device.