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Improved Sixteen Color Palette using Error Diffusion

IP.com Disclosure Number: IPCOM000109145D
Original Publication Date: 1992-Jul-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Miller, IM: AUTHOR

Abstract

Described is an improved sixteen color palette image display using techniques from error and brightness diffusion of a 256 color image.

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Improved Sixteen Color Palette using Error Diffusion

      Described is an improved sixteen color palette image display
using techniques from error and brightness diffusion of a 256 color
image.

      When using a color limited palette, it is possible to
approximate an image that originally had 256 intensity levels in each
of the three primary colors.  However, a sixteen color palette has
colors that are not as orthogonal as they are in a 256 color palette.
This is evident when using any one of several techniques where the
number of colors are in the red, green, or blue space.  Nominally,
the 256 colors are divided in approximately equal steps.  However,
with a sixteen color palette, only three intensities of each color
are present.  These intensities are none, half, and full.  As a
result, the following combinations must be used:
      0  black         8  grey
      1  blue          9  dark blue
      2  red          10  dark red
      3  pink         11  dark pink
      4  green        12  dark green
      5  turquoise    13  dark turquoise
      6  yellow       14  dark yellow
      7  white        15  unused

      The dark colors are half intensities and the others are full
intensities.  Therefore, the following intensities are not attained:
         dark blue - red
         dark blue - green
         dark red - blue
         dark red - green
         dark green - blue
         dark green - red

      To make the coordinate orthogonal, the coordinate system is
divided in two, as follows:
         Black        black
         blue         dark blue
         red     ...