Planar
Encyclopedia
In computer graphics
, planar is the method of representing pixel
colours with several bitplanes
of RAM. Each bit in a bitplane is related to one pixel on the screen. Unlike Chunky, Highcolour
or Truecolour graphics, the whole data for an individual pixel isn't in one specific location in RAM, but spread across the bitplanes that make up the display.
For example, on a chunky display, each byte represents one pixel. Three pixels in a row would be stored as follows, where up to 256 different colours are available:
Byte 0: 00000000 = Black pixel
Byte 1: 00000001 = Blue pixel
Byte 2: 00000010 = Green pixel
Whereas a planar data store could use 2 bitplanes, providing for a 4 colour display:
A row of 8 black pixels:
Plane 0, Byte 0: 00000000
Plane 1, Byte 0: 00000000
A row of 1 blue pixel, 2 black pixels, 1 green pixel, 4 black pixels:
Plane 0, Byte 0: 10000000
Plane 1, Byte 0: 00010000
Adding a third plane would make 23=8 colours available. Where fewer than 256 colours are needed, planar graphics are more economical in RAM compared with chunky graphics. Example: to display 8 colours using 3 bitplanes, so each pixel has 3 bits assigned to it instead of 8, reduces memory and bandwidth requirements by 62.5%. This saving was most significant in the 80s and early 90s when fast RAM was expensive and most computer graphics displayed fewer than 256 colours.
A disadvantage of planar graphics is that more RAM address cycles are needed for scrolling
and animation
s, although these operations can be made faster by dedicated hardware.
Computer graphics
Computer graphics are graphics created using computers and, more generally, the representation and manipulation of image data by a computer with help from specialized software and hardware....
, planar is the method of representing pixel
Pixel
In digital imaging, a pixel, or pel, is a single point in a raster image, or the smallest addressable screen element in a display device; it is the smallest unit of picture that can be represented or controlled....
colours with several bitplanes
BIT plane
This article is about Natalie Jeremijenko and the Bureau of Inverse Technology's project. For the company, see Bitplane. For the digital information term, see bit plane....
of RAM. Each bit in a bitplane is related to one pixel on the screen. Unlike Chunky, Highcolour
Highcolour
High color graphics is a method of storing image information in a computer's memory such that each pixel is represented by two bytes...
or Truecolour graphics, the whole data for an individual pixel isn't in one specific location in RAM, but spread across the bitplanes that make up the display.
For example, on a chunky display, each byte represents one pixel. Three pixels in a row would be stored as follows, where up to 256 different colours are available:
Byte 0: 00000000 = Black pixel
Byte 1: 00000001 = Blue pixel
Byte 2: 00000010 = Green pixel
Whereas a planar data store could use 2 bitplanes, providing for a 4 colour display:
A row of 8 black pixels:
Plane 0, Byte 0: 00000000
Plane 1, Byte 0: 00000000
A row of 1 blue pixel, 2 black pixels, 1 green pixel, 4 black pixels:
Plane 0, Byte 0: 10000000
Plane 1, Byte 0: 00010000
Adding a third plane would make 23=8 colours available. Where fewer than 256 colours are needed, planar graphics are more economical in RAM compared with chunky graphics. Example: to display 8 colours using 3 bitplanes, so each pixel has 3 bits assigned to it instead of 8, reduces memory and bandwidth requirements by 62.5%. This saving was most significant in the 80s and early 90s when fast RAM was expensive and most computer graphics displayed fewer than 256 colours.
A disadvantage of planar graphics is that more RAM address cycles are needed for scrolling
Scrolling
In computer graphics, filmmaking, television production, and other kinetic displays, scrolling is sliding text, images or video across a monitor or display. "Scrolling", as such, does not change the layout of the text or pictures, or but incrementally moves the user's view across what is...
and animation
Animation
Animation is the rapid display of a sequence of images of 2-D or 3-D artwork or model positions in order to create an illusion of movement. The effect is an optical illusion of motion due to the phenomenon of persistence of vision, and can be created and demonstrated in several ways...
s, although these operations can be made faster by dedicated hardware.