Overview: Digital image fundamentals
Image fundamentals describe the pixel grid, transparency, orientation and compression behind a digital picture.
A picture's dimensions identify its stored grid, while transparency and orientation affect how that grid is presented. Compression changes the way the image data are represented and can affect retained detail. These topics establish those properties before an image format or display operation is examined.
Raster images
A raster image describes a rectangular grid of samples whose dimensions, component representation and colour interpretation determine the decoded picture.Image resolution
Image resolution includes pixel dimensions and their relationship to presentation size; megapixels and pixel-density metadata describe different quantities.Image transparency
Transparency tells a compositor how an image contributes over a background, using alpha or a format-specific transparent index rather than an ordinary background colour.Image orientation
Orientation metadata describes a transform from stored image rows and columns to the intended visual direction, including reflections as well as rotations.Image compression
Image compression reduces encoded storage through reversible coding or lossy representation changes, while decoded dimensions and downstream processing remain separate.