Features of Multimedia Signals

Abstract

Feature extraction is the first step towards obtaining content-related information from a multimedia signal, or allowing to compare two signals by feature properties. The usual output of feature extraction is a set of parameters which should be largely invariant against typical distortions and variations that could occur to the signal, such as geometric modifications, noise, illumination, loudness or speed/tempo changes, etc. Feature description methods can be based on statistical, physical or perceptual models, or related to low-level parameterization of the feature properties. Important features of image and video signals are color, texture, edge and corner structures, shape, geometry, motion, depth and spatial (2D/3D) structure. For audio signals, envelopes (hulls) and other properties of the temporal, spectral or cepstral functions, timbre, modulation of tones, loudness, tempo, harmonic structure, melody and structure of music pieces are important features. Some higher-level features can directly be related to semantic meaning.