2. Example: observation of a scene

To illustrate the above general ideas, and in particular the notion of optical signal, let's consider in a more or less qualitative way the case, common in optronics, of imaging or observing a scene, which may be representative of one of the following situations:

• television or infrared imaging, with observation on monitor ;

• satellite earth observation system (spot)...

In each case, the scene is characterized by a set of objects, including the object (or objects) we are trying to detect (recognize, etc.), the backgrounds against which these objects appear, the sources that illuminate the scene (sun, sky, etc.), the propagation media, etc.

Radiation from sources and objects can be calculated at the level of each emitter using radiometric results, for...