Sub-pixel resolution

[citation needed] For example, if the image of a ship of length 50 metres (160 ft), viewed side-on, is 500 pixels long, the nominal resolution (pixel size) on the side of the ship facing the camera is 0.1 metres (3.9 in).

Now sub-pixel resolution of well resolved features can measure ship movements which are an order of magnitude (10×) smaller.

Small movements can however be measured (down to 1 cm) with simple calibration procedures.

It is also important when attempting sub-pixel resolution to keep image noise to a minimum.

This, in the case of a stationary scene, can be measured from a time series of images.