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Browse Prior Art Database

Area Detection in Mixed Pixel Format

IP.com Disclosure Number: IPCOM000117725D
Original Publication Date: 1996-May-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 4 page(s) / 61K

Publishing Venue

IBM

Related People

Fujita, N: AUTHOR [+3]

Abstract

Disclosed is a video system for overlaying computer graphics with a natural picture. For natural pictures, the pixel data format normally used is YUV4:2:2. In order to have natural picture overlay capability, it is important that the video system supports the mixed pixel format, which are RGB565 and YUV4:2:2. When both format data are in a video memory, the video system must detect to which data format each pixel data conforms.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 80% of the total text.

Area Detection in Mixed Pixel Format

      Disclosed is a video system for overlaying computer graphics
with a natural picture.  For natural pictures, the pixel data format
normally used is YUV4:2:2.  In order to have natural picture overlay
capability, it is important that the video system supports the mixed
pixel format, which are RGB565 and YUV4:2:2.  When both format data
are in a video memory, the video system must detect to which data
format each pixel data conforms.

      For example, consider a case where the display resolution is
1024x768x16 bit color.  The structure of 16 bit video data in RGB565
format is defined as in Fig. 1.  Otherwise, the data structure of 16
bit YUV data is defined as Figs. 2 and 3.

      Both U and V actually take value between -0.5 and 0.5.  To
treat them as digital value, these are added to +0.5 and described as
digital value between 00h to ffh.

      The circuit block diagram is shown in Fig. 4.  A Cathode Ray
Tube (CRT) Controller (CRTC) continuously reads pixel data from the
video memory, and then the pixel data are appropriately converted
into either of the formats before being sent to a Digital to Analog
Converter (DAC).  A switch controller is watching a pixel data.  When
or if it finds the key color data, then it turns the switch to a YUV
converter, because such key color data indicates a beginning point of
overlay on the scan line.  If the switch controller finds "0000" data
as YUV format or detects H-...