Information AboutPlanar |
For the corporation, see Planar Systems . Something is called planar if it is made up of flat Plane s, or pertaining to planes. A Graph is called planar if it can be drawn in the plane without any edge intersections; see Planar Graph . In the context of Computer Graphics , Planar is method of representing pixel information with several ''bitplanes''. There are also cases where byteplanes have been used. Each individual bit in a bitplane is related to a single pixel on the screen. Unlike Chunky , Highcolour or Truecolour graphics, the 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 will represent one pixel. So, if colour zero is black, colour one is blue, and colour two is green, a byte of chunky pixel data would look like this: 00000000 = Black pixel 00000001 = Blue pixel 00000010 = Green pixel Whereas planar data would look like this: Plane 0, Byte 0: 00000000 = 8 black pixels Plane 1, Byte 0: 00000000 Plane 0, Byte 0: 10000000 = 6 black pixels, one blue pixel, one green pixel Plane 1, Byte 0: 00010000 Planar graphics were used a lot in the 80s and early 90s because displays tended to only be able to show fewer than 256 colours. Chunky displays always represent one pixel within a contigous grouping of bits. And usually have 1 byte or more per pixel, even with a colour depth not a multiple 8 bits (sometimes going as far as storing a 24 bit image in 32 bit chunks). This wastes RAM in cases where fewer bits are needed than are provided. If you only need to display 8 colours, you can use 3 bitplanes, and each pixel only has 3 bits assigned to it instead of 8 (reducing memory and bandwidth requirements by 62.5%). |
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