rasternoun [ C ]
uk/ˈræs.tər//ˈræs.tɚ/specializeda rectangular pattern of lines that an electron beam follows on a television or computer screen:
The characters can be exposed line by line using a raster scan.
a type of computer image that is based on a rectangular grid (= pattern of lines and columns) of pixels (= small dots):
PNG is a graphics file format for raster images.