rasterformat

Rasterformat refers to digital image file formats that encode images as a grid of pixels, in contrast to vector formats that describe shapes. Each pixel stores color or brightness information, and the image is defined by its resolution and color depth. Raster formats are widely used for photographs, web images, and satellite or medical imaging because they faithfully represent continuous-tone scenes.

Common properties of raster formats include resolution, color depth, and compression. Color is usually represented in RGB or CMYK color models, and images may include an alpha channel for transparency. Raster formats employ compression, which can be lossless (preserving all data, as in PNG and TIFF) or lossy (reducing data to save space, as in JPEG and WebP). File sizes depend on resolution, color depth, and the chosen compression. Metadata such as EXIF data and ICC color profiles may be embedded; some formats, like GeoTIFF, support georeferencing for mapping applications.

Examples of widely used raster formats include PNG, JPEG, TIFF, BMP, GIF, and WebP. Each serves different needs: GIF is limited to 256 colors and supports animation, TIFF is flexible for professional workflows, and JPEG is common for photographs. Raster formats are inherently resolution-dependent, so scaling can degrade quality; they are generally not suitable for scalable vector graphics without rasterization.

In recent years, raster formats have incorporated features such as higher bit depths, alpha channels, and advanced compression. Newer formats like WebP and AVIF offer improved compression efficiency for web use, while RAW formats capture sensor data for post-processing. The choice of raster format depends on quality requirements, color management, transparency needs, and the intended distribution medium.