Browse Prior Art Database

Automatic 9th PEL Drop

IP.com Disclosure Number: IPCOM000114943D
Original Publication Date: 1995-Feb-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Ishikawa, T: AUTHOR [+2]

Abstract

To display Video Graphics Array (VGA) mode 3+ (horizontal width is 720 dots) on 640-dot width Liquid Crystal Display (LCD) panel, screen image must be compressed by dropping 80 dots (80=720-640) per each line. Genarally, in this case, 9th pel of each characters are dropped because 9th pel of all characters are blank (except for special graphic characters). So 9th pel must be detected correctly, or character fonts are distorted.

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Automatic 9th PEL Drop

      To display Video Graphics Array (VGA) mode 3+ (horizontal width
is 720 dots) on 640-dot width Liquid Crystal Display (LCD) panel,
screen image must be compressed by dropping 80 dots (80=720-640) per
each line.  Genarally, in this case, 9th pel of each characters are
dropped because 9th pel of all characters are blank (except for
special graphic characters).  So 9th pel must be detected correctly,
or character fonts are distorted.

      This method can detect 9th pel correctly even if there are
reversed-characters or special graphic characters are displayed.

      As shown in the Figure, detection areas are set.  Vertically
color-changed point of images in the entire screen is counted at the
vertical position 1 to 9 of area independently.  That means there are
9 counters corresponding to the position of 1 to 9.  In this Figure,
position 3 is the lowest color changes.  Then the position 3 is
thought to be 9th pel in character box to be dropped.

      This method is effective not only for VGA mode 3+ but other
modes or other video signals like XGA, SXGA etc.