offsetkorrigering

Offsetkorrigering is the process of removing a fixed bias added to a measurement or signal by sensor electronics or readout circuitry. The offset is a constant value that shifts the baseline of the signal and is independent of the true input. Common causes include electronic offsets in amplifiers, ADC nonzero codes, and dark current in imaging sensors. Offsets can drift with temperature, time, or operating conditions, making regular calibration important.

Applications and methods vary by domain. In imaging and astronomy, offsetkorrigering is often implemented by subtracting a bias frame or applying a per-pixel offset map to raw data, followed by dark-frame corrections. In audio and general data acquisition, DC offset removal is performed through baseline subtraction, high-pass filtering, or calibration against a known zero-input signal. In instrumentation and process control, offset compensation adjusts sensor outputs to align with a reference, sometimes alongside gain calibration to correct both bias and sensitivity.

Implementation considerations include whether offsets are uniform across a sensor or spatially varying. A global offset can be subtracted from the entire signal, while a per-channel or per-pixel offset map may be required for nonuniform electronics. Offsets may depend on temperature, time, or hardware aging, necessitating periodic recalibration and temperature compensation.

Limitations and pitfalls include the risk of removing legitimate low-frequency content if aggressive high-pass filtering is used, and the potential amplification of noise when the offset is poorly estimated. Proper calibration aims to minimize bias without distorting the true signal or introducing artifacts.

See also: bias calibration, dark-frame subtraction, gain calibration, DC offset removal, baseline correction.