Browse Prior Art Database

Multi-Grayscaling Control using Window Attribute

IP.com Disclosure Number: IPCOM000113700D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 4 page(s) / 115K

Publishing Venue

IBM

Related People

Aruga, N: AUTHOR [+3]

Abstract

To increase the number of colors on the flat panel, there are digital half-toning techniques such as Dithering, Frame Rate Control and Error Diffusion.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Multi-Grayscaling Control using Window Attribute

      To increase the number of colors on the flat panel, there are
digital half-toning techniques such as Dithering, Frame Rate Control
and Error Diffusion.

      In the conventional method, only one method is selected and the
modulation is applied on whole screen image.  Though these method
increase the number of colors, Dithering reduces screen resolution,
Frame Rate Control will cause flicker and Error Diffusion will
produce worm trace.  In the case of the multi-window system, it
happens that selecting one method appropriate for one window will
result in the loss of image quality of the rest of the windows.

      This Multi-Grayscaling Control using Window Attribute is the
method to check the window attribute and apply different modulation
methods which is appropriate for each window on the screen.  It
increases the number of colors of the selected windows while keeping
the same image quality in other screen area.

      Conventional Method - In X-Window, the pixel data is stored in
the frame buffer and the window attribute, which is associated with
each pixel data, is used to select one of the color palettes for the
window.

      Though the video data is R,G,B 8 bits each, current flat panel
can support only R,G,B 4 bits each and the lower 4 bits are normally
dropped.  In the conventional method, to increase the number of color
on the flat panel, there are grayscaling techniques such as
Dithering, Frame Rate Control and Error Diffusion.  Dithering is
suitable for natural image, FRC is suitable for graphics, and Error
Diffusion is suitable for motion picture.  These techniques increase
the number of colors using space or timing modulation, based on the
information of the lower 4bits.

      Though these method increase the number of colors, Dithering
reduces screen resolution, Frame Rate Control will cause flicker and
Error Diffusion will produce worm trace.  In the conventional method,
Device Driver or H/W checks the screen mode and control the
modulation to be enabled or disabled.  In normal case, these
modulations are enabled only in the graphics mode and disabled in the
text mode.  This is very useful in the single window system, since
one application software...