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From: sdh@joevax.UUCP (The Doctor)
Newsgroups: net.graphics
Subject: jaggie remover
Message-ID: <281@joevax.UUCP>
Date: Wed, 17-Sep-86 18:03:16 EDT
Article-I.D.: joevax.281
Posted: Wed Sep 17 18:03:16 1986
Date-Received: Wed, 24-Sep-86 22:13:20 EDT
Distribution: net
Organization: Bell Communications Research Inc., Morristown, NJ
Lines: 56


Ok, here is a snippet of code to smooth out all jaggies in an image

#define VERTRES  some integer
#define HORZRES  some integer

struct attr {
	/* whatever you need to define a pixel */
}

smooth()
{
	register int x, y;
	struct attr average[3][HORZRES], avgpix();

	for (y = 0; y < VERTRES + 2; y++) {
		for (x = 0; x < HORZRES; x++) {
			if (y>2) {
				/* change pixel only after its out of range */
				diddle(average[(y - 2) % 3][x], x, y);
			}
			if (y < VERTRES) {
				/* save pixel average only while on screen */
				average[y % 3][x] = avgpix(x, y);
			}
		}
	}
}
stuct attr avgpix(x, y)
int x, y;
{
	/* this routine should average all the attributes of the 8
	 * pixels around x,y and x,y
	 * and return the averages.
	 */
}
diddle(avg, x, y)
struct attr avg;
int x, y;
{
	/* this routine should get the attributes for the pixel at x,y
	 * and change them according some function of their difference.
	 */

	struct attr curr_pixel;

	curr_pixel = get_attr(x, y);
	/* diddle it here */
	set_attr(curr_pixel, x, y);
}

That's it.  It should work very well on objects with plain backgrounds.
On very complex pictures it will probably give the effect of going out of focus.

Steve Hawley
joevax!sdh