Glossary

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Perceptual Hashing(also: Image Hashing, pHash)

A technique that generates a compact fingerprint (hash) of an image based on its visual content rather than its raw data. Unlike cryptographic hashes that change completely with any modification, perceptual hashes produce similar values for visually similar images, allowing…

Phase-Based Motion Processing(also: Phase-Based Video Motion Processing, Phase-Based Motion Magnification)

A family of computer vision techniques that decompose video frames into complex steerable pyramids and analyse changes in the temporal phase of each scale and orientation to recover motion, including sub-pixel movements invisible to the naked eye. Because it operates in the…

Point Spread Function(also: PSF)

A mathematical description of how a single point of light is spread or blurred by an optical system such as the human eye. The point spread function characterizes the degree and pattern of distortion introduced by optical aberrations. In accessibility research, PSFs are used to…

Pre-compensation(also: Display Pre-compensation, Image Pre-compensation)

A technique in which images displayed on a computer screen are mathematically modified in advance to counteract the visual aberrations of the viewer's eye. Rather than relying on corrective lenses or magnification, pre-compensation transforms the source image so that when it…

Precompensation(also: Display Precompensation, Image Precompensation)

A technique in visual accessibility that pre-modifies displayed images in a way that is opposite to the optical distortion introduced by a user's eye, so that the image arriving at the retina more closely resembles the intended original. Precompensation works analogously to an…

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