Raster graphics (also called bitmap) is one of the two type of image.
The image is represented as dot matrix data structure.
A raster is technically characterized by the:
A bitmap is a single-bit raster.
The word raster comes from the Latin word rastrum, or rake. Old cathode ray tubes created images on screens by literally drawing one line at a time, raking each across the screen.
Image can also be expressed logically as vector to reduce the storage overhead.
Rasterized images are designed to work at a specific resolution.
A higher high-resolution displays needs to scale them up to appear the same size, losing information in the transformation.
Vector images never have this problem
An image have:
The term Intrinsic is also known as natural. Ref - Object-Sizing Terminology CSS Images Module Level 3
The bitmap image uses anti-aliasing, a method of using grayscale to attempt to smooth the drawing when the image is scaled up.