Raster

Raster refers to a rectangular grid of picture elements (pixels) used to represent a digital image. Each pixel contains a value or set of values describing color and brightness, and the grid resolution determines the level of detail. Raster images are usually resolution dependent: increasing scale magnifies pixels, often revealing jagged edges or blurring.

In geographic information systems (GIS) and remote sensing, raster is a data model that stores information as a grid of cells. Each cell holds a value representing a measured quantity such as elevation, land cover, temperature, or reflectance. Cell size controls spatial resolution; smaller cells capture finer detail but require more storage. Raster data are often stored in formats such as GeoTIFF, IMG, or netCDF, and may include georeferencing to link cells to real-world coordinates.

Rasterization is the process of converting vector graphics or 3D models into a raster image by determining the color value for each grid cell through sampling and shading. This stage is part of the rendering pipeline in computer graphics and can introduce artifacts such as aliasing if not properly filtered.

Rasters are contrasted with vector data, which represent images as geometric primitives such as points, lines, and polygons. Raster advantages include simple image processing and efficient representation of continuous data; limitations include large file sizes and loss of precision when scaling.

Common raster formats and applications: raster graphics in digital photography and web images; satellite imagery and elevation models in GIS; medical imaging such as CT or MRI slices.