Abstract: An improved pixel structure for a logarithm response image sensor. The pixel structure and read-out sequence provides a method to get a signal free from offsets and gain mismatch due to nonuniformities in the device parameters. An additional transistor is added to a basic logarithmic response pixel structure in order to provide a means for producing a calibration signal level. The calibration transistor is either coupled within the pixel structure itself, or to an extra column line that is coupled to a voltage source. The calibration transistor is therefore not coupled to an extra column line with a calibration current source, and therefore does not have the additional circuitry, power consumption, or control issues associated with a calibration current source type method.