cunniff@hpesoc1.HP.COM (Ross Cunniff) (10/17/87)
While wasting time with my 1000 last night, I noticed an interesting effect:
if you create a high-contrast pattern of alternating colors, an interference/
shadowing/ghosting/whatever pattern appears. Repeat by:
Go into Deluxe Paint, 640x200 mode.
Fill the screen with a pattern like (R = red, B = black)
RBRBRBRBRBRBRB...
RBRBRBRBRBRBRB...
RBRBRBRBRBRBRB...
RBRBRBRBRBRBRB...
RBRBRBRBRBRBRB...
.
.
.
(you get the idea)
The screen will now have a pattern of several intersecting
curves of bright and dark areas. At the very center of
the screen, the brighter pixel groups will form a
hexagonal packing pattern, which "spirals" outward toward
the screen edges.
Any ideas on what causes this? Is it an interference pattern caused
by the mask, or what? Can anything be done about it (short of
buying a different monitor) - it IS rather pretty, but I wouldn't
want to look at it all the time.
Ross Cunniff
...{hplabs,ucbvax}!hpda!cunniff
cunniff%hpda@hplabs.ARPAjdow@gryphon.CTS.COM (Joanne Dow) (10/20/87)
In article <4200002@hpesoc1.HP.COM> cunniff@hpesoc1.HP.COM (Ross Cunniff) writes: >While wasting time with my 1000 last night, I noticed an interesting effect: >if you create a high-contrast pattern of alternating colors, an interference/ >shadowing/ghosting/whatever pattern appears. Repeat by: > > Go into Deluxe Paint, 640x200 mode. > Fill the screen with a pattern like (R = red, B = black) > > RBRBRBRBRBRBRB... > RBRBRBRBRBRBRB... > RBRBRBRBRBRBRB... > RBRBRBRBRBRBRB... > RBRBRBRBRBRBRB... > > The screen will now have a pattern of several intersecting > curves of bright and dark areas. At the very center of > the screen, the brighter pixel groups will form a > hexagonal packing pattern, which "spirals" outward toward > the screen edges. > >Any ideas on what causes this? This is called a moire' pattern. One of the thngs it can be used for in that precise configuration is a precision alignment of the monitor's sweep linearity. It is an interference between your paint pattern and the dots on the screen. -- <@_@> BIX:jdow INTERNET:jdow@gryphon.CTS.COM UUCP:{akgua, hplabs!hp-sdd, sdcsvax, ihnp4, nosc}!crash!gryphon!jdow Remember - A bird in the hand often leaves a sticky deposit. Perhaps it was better you left it in the bush with the other one.