Posterior sampling - Posterior sampling generates draws from, or approximately from, a posterior probability distribution.
Power spectrum - A power spectrum describes how a signal's power or squared-amplitude content is distributed across frequencies.
Preconditioning - Preconditioning transforms a numerical problem into an equivalent or suitably related form that is easier for an iterative solver to handle.
Prefilter (anti-aliasing) - An anti-aliasing prefilter reduces signal content that a subsequent sampling step cannot represent reliably.
Preimage - A preimage is an input, or a set of inputs, that maps to a specified output under a function.
Prim's algorithm - Prim's algorithm finds a minimum spanning tree of a connected, weighted, undirected graph.
Prior (regularizer) - A prior is a model's probability distribution or preference over possible solutions before incorporating the current observation.
Probabilistic relaxation labeling - Probabilistic relaxation labeling is an iterative method for refining uncertain labels using compatibility relationships among neighboring items.
Provisioning - Provisioning is the process of making required computing resources or access available and configuring them for use.
Pyramid (image processing) - An image pyramid is a collection of representations of the same image at progressively coarser scales or resolutions.
Pyramid vector quantization - Pyramid vector quantization, or PVQ, is a structured method for approximating a vector using codewords based on integer vectors whose absolute components...
Quadrature mirror filter - A quadrature mirror filter, or QMF, is a filter used in a filter-bank arrangement that separates a signal into complementary frequency bands.
Quantization error - Quantization error is the difference between an original value and the discrete value used to represent it after quantization.
Radon transform - The Radon transform represents a function through its integrals over lines.
Random sample consensus - Random sample consensus, usually called RANSAC, is a robust model-fitting method that repeatedly fits candidate models to small random subsets and evaluates...
Ratio test - The ratio test is a feature-matching rule that compares the distance to a descriptor's nearest candidate with the distance to its second-nearest candidate.
Re-detection - Re-detection is the process of locating a previously tracked target again after tracking has failed, become uncertain or been interrupted.
Read noise - Read noise is random uncertainty introduced by the electronic process of measuring and reading a sensor's signal.
RED (Regularization by Denoising) - Regularization by Denoising, or RED, is an image-reconstruction framework that uses a denoiser to supply a preference for plausible images while fitting...
Reduce (pyramid operator) - Reduce is an image-pyramid operation that creates a smaller, coarser representation of an image, typically by low-pass filtering followed by subsampling.
Reflection removal - Reflection removal is the process of estimating and reducing an unwanted reflected image component, commonly in photographs taken through glass.
Region growing - Region growing is a segmentation approach that starts from one or more seed locations and expands regions by adding neighboring elements that satisfy a...
Region of interest - A region of interest, or ROI, is a selected part of an image, video frame or other dataset that receives particular attention or processing.
Reinhard operator - The Reinhard operator is a tone-mapping approach associated with photographic tone reproduction that compresses high-dynamic-range luminance for a...
Relative pose - Relative pose describes the rotation and translation relating two coordinate frames, such as two camera views.
Relaxation labeling - Relaxation labeling is an iterative method for reducing ambiguity in a set of label assignments by using relationships among the items being labeled.
Remosaic - Remosaic is a sensor-processing operation that converts data from one color-filter-array arrangement into another mosaic representation, often from grouped...
Remote photoplethysmography - Remote photoplethysmography, often abbreviated rPPG, estimates a blood-volume-related pulse signal from subtle changes in light recorded by a camera...
Ridge detection - Ridge detection identifies elongated structures that are locally high or low relative to neighboring values across their width.
Roberts cross gradient operator - The Roberts cross gradient operator estimates local image-intensity change using two diagonal differences across a 2×2 neighborhood.
Robust combination (sigma-clipping) - Sigma-clipping is an iterative rejection procedure that identifies values sufficiently far from an estimated center relative to an estimated spread.
Robust regression - Robust regression is a family of methods for estimating relationships while limiting sensitivity to specified departures from modeling assumptions, often...
Robust statistics - Robust statistics studies and develops methods that remain reasonably stable under specified departures from their assumptions.
Rolling-shutter correction - Rolling-shutter correction compensates for geometric distortions caused when different parts of an image are exposed at different times while the camera or...
Saliency - In visual perception and computer vision, saliency describes how strongly a location or feature stands out within a scene under a stated model of attention.
Salt-and-pepper noise - Salt-and-pepper noise is an image corruption pattern in which affected samples take very low or very high intensity values, often appearing as scattered...
Saturation (point operation) - A saturation point operation changes the color intensity of each pixel relative to a neutral gray reference, using only that pixel's input values.
Scale space - Scale space is a framework for representing an image or signal at multiple levels of spatial detail.
Scale-space axioms - Scale-space axioms are mathematical requirements used to define what a family of progressively coarser image representations should do.
Scanpath - A scanpath is an ordered description of where a person's gaze moves while viewing a stimulus, often represented as a sequence of fixations linked by saccades.
Scatter matrix - A scatter matrix summarizes multivariate variation through sums of outer products of centered observation vectors.
Seam carving - Seam carving is a content-aware image-resizing technique that removes or inserts connected paths of pixels called seams.
Segmentation - In computer vision, segmentation divides an image or related visual representation into regions or assigns labels at a fine spatial level, commonly per pixel.
Self-similarity matrix - A self-similarity matrix compares elements of a sequence or collection with other elements of the same sequence or collection.
Semantic gap - The semantic gap is the mismatch between information represented or extracted by a computational system and the meaning people attach to that information in...
Separable filter - A separable spatial filter has a multidimensional kernel that can be expressed as a product of lower-dimensional kernels.
Shadow removal - Shadow removal is the process of producing an image or representation in which the effects of selected shadows are reduced or compensated for.