English Amiga Board - View Single Post - Amiga Bitplanes & Planar vs Chunky

CodyJarrett · 12 November 2009, 11:14

Memory Storage and Colours

A computer display is made up of individual pixels each of which can have a specific colour. A two colour display needs only two numbers to record each possible colour in memory; 0 and 1, where 0 might represent black and 1 might represent white. In binary terms only 1 bit of memory is required to store each pixel's colour.

The more colours are used the more memory is required for each pixel. For example, 16 colours can be stored in 4 bits - decimal 0 or binary 0000 to decimal 15 or binary 1111) and 256 colours could be stored in 8 bits (1 byte) - decimal 0 or binary 00000000 to decimal 255 or 11111111.

The number of colours clearly affects how much memory is used and how many memory addresses must be accessed to update the display.

In order to work out how many colours can be displayed using the Amiga’s bitplanes calculate:

2 power y where y is the number of bitplanes

Bitplanes
1 = 2 colours
2 = 4 colours
3 = 8 colours
4 = 16 colours
5 = 32 colours
6 = 64 colours
7 = 128 colours
8 = 256 colours

The number of bitplanes most commonly used on the Amiga are 4 (16 colours), 5 (32 colours) and 8 (256 colours e.g. AGA).

12 November 2009, 11:14	#5
CodyJarrett Global Moderator Join Date: Mar 2001 Location: UK Age: 46 Posts: 6,160	Memory Storage and Colours Memory Storage and Colours A computer display is made up of individual pixels each of which can have a specific colour. A two colour display needs only two numbers to record each possible colour in memory; 0 and 1, where 0 might represent black and 1 might represent white. In binary terms only 1 bit of memory is required to store each pixel's colour. The more colours are used the more memory is required for each pixel. For example, 16 colours can be stored in 4 bits - decimal 0 or binary 0000 to decimal 15 or binary 1111) and 256 colours could be stored in 8 bits (1 byte) - decimal 0 or binary 00000000 to decimal 255 or 11111111. The number of colours clearly affects how much memory is used and how many memory addresses must be accessed to update the display. In order to work out how many colours can be displayed using the Amiga’s bitplanes calculate: 2 power y where y is the number of bitplanes Bitplanes 1 = 2 colours 2 = 4 colours 3 = 8 colours 4 = 16 colours 5 = 32 colours 6 = 64 colours 7 = 128 colours 8 = 256 colours The number of bitplanes most commonly used on the Amiga are 4 (16 colours), 5 (32 colours) and 8 (256 colours e.g. AGA).