Browse Prior Art Database

Color Display System

IP.com Disclosure Number: IPCOM000117491D
Original Publication Date: 1996-Mar-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Mizuno, T: AUTHOR [+3]

Abstract

Disclosed is a system of hardware for high speed dithering for color video displays which have four look-up tables and switches the tables according to the pixel signal (565 RGB or 555 RGB) and the pixel position.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 72% of the total text.

Color Display System

      Disclosed is a system of hardware for high speed dithering for
color video displays which have four look-up tables and switches the
tables according to the pixel signal (565 RGB or 555 RGB) and the
pixel position.

      To reduce the cost of display hardware, Note_PC generally
adopts color-limiting scheme called palettization and maximum colors
of palette are 256 (8 bits colors).  In order to maintain color
fidelity, it is necessary to employ a color averaging technique, such
as dithering, to simulate the colors of the higher resolution image
with limited colors of the palette.

      Currently, the dithering is done by software but it is not
sufficient in speed to display a moving image.

      This hardware consists of two parts, one is dithering, another
is First In First Out (FIFO) buffer.

      The dithering portion is made up of two binary counters
(Counter #1 and Counter #2) and a four-bank L.U.T. (look up table).
Counter #1 counts the horizontal position of a pixel and Counter #2
counts horizontal lines.  The four-bank L.U.T is made up of 64k bytes
x 4 banks RAM table which data are re-writable from CPU BUS.  Pixel
positions on a display and the four-bank L.U.T are shown in Figs. 1
and 2.

      A 2 by 2 dither matrix is used.  The number on pixel is
corresponding to the number of bank of L.U.T. which applied to
convert a pixel signal (16 bits 565 RGB or 555 RGB) to a palette
point(8 bits data).  Bank selecti...