Raster graphics are represented by a grid of pixels stored in an image file. The image is characterized by its width, height in pixels and color depth. Raster images correspond bit-for-bit to what is displayed on screen and stored in video memory. The word raster comes from the Latin word for rake, originally referring to the line-by-line scanning of CRT video monitors.

1. Raster graphics

2. • In computer graphics, a raster graphics
image or bitmap is a data structure
representing a generally rectangular grid
of pixels, or points of color, viewable via a
monitor, paper, or other display medium.

3. • Raster images are stored in image files
with varying formats .

4. • A bitmap corresponds bit-for-bit with an
image displayed on a screen, generally in
the same format used for storage in the
display's video memory, or maybe as a
device-independent bitmap.

5. • A bitmap is technically characterized by
the width and height of the image in pixels
and by the number of bits per pixel (a color
depth, which determines the number of
colors it can represent).

6. • The printing and prepress industries know
raster graphics as contones (from
"continuous tones") and refer to vector
graphics as "line work".

7. Etymology
• The word "raster" has its origins in the
Latin rastrum (a rake), which is derived
from radere (to scrape).

8. • It originally referred to the raster scan of
cathode ray tube (CRT) video monitors,
which paint the image line by line by
magnetically steering a focused electron
beam.

9. • By association, it came also to refer to a
rectangular grid of pixels. See also
rastrum, a device for drawing musical staff
lines.