Signal transfer function

Specifically, in the field of image analysis, it gives a measure of the noise of an imaging system, and thus yields one assessment of its performance.

An operator, using computer software, defines an arbitrary area, with a given set of data points, within the signal and background regions of the output image of the infrared sensor, i.e. of the unit under test (UUT), (see "Half Moon" image below).

A second order polynomial curve is fitted to the data of each line.

The signal input of the UUT is within its own spectral response.

The slope of the linear portion of this curve is then found using the method of least squares.

All the data points in the linear region of the SiTF curve can be used in the method of least squares to find a linear approximation.

The red line is the SiTF . As can be seen, a line is fitted to the linear portion of the signal output versus signal input of an infrared sensor .
Half moon target – on the left the image of the background region and on the right an image of the signal region. Using specialized software, an operator arbitrarily defines an area of evaluation in both regions to be used in determining the signal transfer function.