Light information devices were created a long time before the information theory was developed, and the features of these devices were described by the common optical characteristics. However, these characteristics look insufficient for these devices information abilities definition, and the need for specific information characteristics has become apparant. Along with that, the common methods for optical characteristics estimation must be applied for the definition of information characteristics. It has been necessary to compare some optical characteristics (input signal value expressed in amplitude and phase, resolving power, signal distribution by light wavelengths or color components, by polarization plane position, and by time intervals) with the information ones. In order to come to information characteristics, it was necessary to perform optical signal and object (and image) light field digitization. In this work we discuss and compare different methdos of the signal and image light field division into different componenets (freedom degrees): determined, statistical, and system-based.