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From: jones@pyrite.cs.uiowa.edu (Douglas W. Jones,201H
 MLH,3193350740,3193382879)
Newsgroups: rec.arts.ascii,alt.ascii-art,alt.binaries.pictures.ascii
Subject: LINE - Hilbert curves
Date: 7 Jun 1994 21:11:24 GMT
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I wrote an image processing program some time ago to explore the effect
of replacing raster scanning with Hilbert curve scanning, and a side
effect of this work was a little program that generates hilbert curves:

% filltest 2 2
._.
._!
%
% filltest 4 4
. ._._.
!_! ._!
._. !_.
! !_._!
%
% filltest 8 8
._. ._._. ._._.
._! !_. !_! ._!
! ._. ! ._. !_.
!_! !_! ! !_._!
._. ._. ! ._._.
! !_! ! !_! ._!
!_. ._! ._. !_.
._! !_._! !_._!
%
% filltest 16 16
. ._._. ._._. ._._. ._._. ._._.
!_! ._! !_. !_! ._! !_. !_! ._!
._. !_. ._! ._. ! ._. ! ._. !_.
! !_._! !_._! ! !_! !_! ! !_._!
!_. ._._._. ._! ._. ._. ! ._._.
._! !_. ._! !_. ! !_! ! !_! ._!
! ._. ! ! ._. ! !_. ._! ._. !_.
!_! !_! !_! !_! ._! !_._! !_._!
._. ._. ._. ._. !_. ._._. ._._.
! !_! ! ! !_! ! ._! !_. !_! ._!
!_. ._! !_. ._! ! ._. ! ._. !_.
._! !_._._! !_. !_! !_! ! !_._!
! ._._. ._._. ! ._. ._. ! ._._.
!_! ._! !_. !_! ! !_! ! !_! ._!
._. !_. ._! ._. !_. ._! ._. !_.
! !_._! !_._! !_._! !_._! !_._!
%
% filltest 32 32
._. ._._. ._._. ._._. ._._. ._._. ._._. ._._. ._._. ._._. ._._.
._! !_. !_! ._! !_. !_! ._! !_. !_! ._! !_. !_! ._! !_. !_! ._!
! ._. ! ._. !_. ._! ._. ! ._. ! ._. !_. ._! ._. ! ._. ! ._. !_.
!_! !_! ! !_._! !_._! ! !_! !_! ! !_._! !_._! ! !_! !_! ! !_._!
._. ._. ! ._._. ._._. ! ._. ._. !_. ._._._. ._! ._. ._. ! ._._.
! !_! ! !_! ._! !_. !_! ! !_! ! ._! !_. ._! !_. ! !_! ! !_! ._!
!_. ._! ._. !_. ._! ._. !_. ._! ! ._. ! ! ._. ! !_. ._! ._. !_.
._! !_._! !_._! !_._! !_._! !_. !_! !_! !_! !_! ._! !_._! !_._!
! ._._. ._._. ._. ._._. ._._. ! ._. ._. ._. ._. !_. ._._. ._._.
!_! ._! !_. !_! !_! ._! !_. !_! ! !_! ! ! !_! ! ._! !_. !_! ._!
._. !_. ._! ._. ._. !_. ._! ._. !_. ._! !_. ._! ! ._. ! ._. !_.
! !_._! !_._! ! ! !_._! !_._! ! ._! !_._._! !_. !_! !_! ! !_._!
!_. ._._._. ._! !_. ._._._. ._! ! ._._. ._._. ! ._. ._. ! ._._.
._! !_. ._! !_. ._! !_. ._! !_. !_! ._! !_. !_! ! !_! ! !_! ._!
! ._. ! ! ._. ! ! ._. ! ! ._. ! ._. !_. ._! ._. !_. ._! ._. !_.
!_! !_! !_! !_! !_! !_! !_! !_! ! !_._! !_._! !_._! !_._! !_._!
._. ._. ._. ._. ._. ._. ._. ._. ! ._._. ._._. ._._. ._._. ._._.
! !_! ! ! !_! ! ! !_! ! ! !_! ! !_! ._! !_. !_! ._! !_. !_! ._!
!_. ._! !_. ._! !_. ._! !_. ._! ._. !_. ._! ._. ! ._. ! ._. !_.
._! !_._._! !_. ._! !_._._! !_. ! !_._! !_._! ! !_! !_! ! !_._!
! ._._. ._._. ! ! ._._. ._._. ! !_. ._._._. ._! ._. ._. ! ._._.
!_! ._! !_. !_! !_! ._! !_. !_! ._! !_. ._! !_. ! !_! ! !_! ._!
._. !_. ._! ._. ._. !_. ._! ._. ! ._. ! ! ._. ! !_. ._! ._. !_.
! !_._! !_._! !_! !_._! !_._! ! !_! !_! !_! !_! ._! !_._! !_._!
!_. ._._. ._._. ._._. ._._. ._! ._. ._. ._. ._. !_. ._._. ._._.
._! !_. !_! ._! !_. !_! ._! !_. ! !_! ! ! !_! ! ._! !_. !_! ._!
! ._. ! ._. !_. ._! ._. ! ._. ! !_. ._! !_. ._! ! ._. ! ._. !_.
!_! !_! ! !_._! !_._! ! !_! !_! ._! !_._._! !_. !_! !_! ! !_._!
._. ._. ! ._._. ._._. ! ._. ._. ! ._._. ._._. ! ._. ._. ! ._._.
! !_! ! !_! ._! !_. !_! ! !_! ! !_! ._! !_. !_! ! !_! ! !_! ._!
!_. ._! ._. !_. ._! ._. !_. ._! ._. !_. ._! ._. !_. ._! ._. !_.
._! !_._! !_._! !_._! !_._! !_._! !_._! !_._! !_._! !_._! !_._!
%
% filltest 19 9
._. ._._. ._._. ._._. ._._. ._._. ._.
._! !_. !_! ._! !_. !_! ._! !_. !_! !
! ._. ! ._. !_. ._! ._. ! ._. ! ._. !
!_! !_! ! !_._! !_._! ! !_! !_! ! !_!
._. ._. ! ._._. ._._. ! ._. ._. !_. .
! !_! ! !_! ._! !_. !_! ! !_! ! ._! !
!_. ._! ._. !_. ._! ._. !_. ._! ! ._.
._! !_._! !_._! !_._! !_._! !_. !_! !
!_._._._._._._._._._._._._._._! ._._.
%
The final example above shows that the program does some odd things
when you ask it to fill a region that isn't a power-of-two square,
but what it does, in that case, didn't matter in the least for my
data compression application.

				Doug Jones
				jones@cs.uiowa.edu