Perceptual coding

Perceptual coding is a method of lossy data compression that exploits the limitations of human sensory system in order to reduce data size. It is widely applied in audio, image and video compression standards, where certain details are removed or simplified because they are unlikely to be noticed under regular listening or viewing conditions. Perceptual coding is based on models of human hearing and vision, such as those studied in psychoacoustics and psychovisual research. By discarding or reducing components of a signal that fall below perceptual thresholds, it achieves significant reductions in bit rate while maintaining a subjectively acceptable quality. Applications Perceptual coding is central to many everyday technologies, including: Audio compression: Formats such as MP3, AAC, and Opus apply psychoacoustic models to remove inaudible frequencies or sounds masked by louder ones. Image compression: Standards such as JPEG rely on psychovisual principles, such as chroma subsampling (reducing color resolution relative to brightness). Video compression: Standards such as MPEG-2, H.264/AVC, and HEVC use similar compression methods as image compression and add other principles, such