Formeln gesucht

[LDIR]

Hat Jemand einen Link oder nähere Informationen über Floyd- Steinberg Algorythmus. Ordered Dithering ist mir inzwischen bekannt und ich kann es anwenden (außer wenn ich Farbbilder als Ergebnis haben will), aber mit FS bekommt man bessere Ergebnise, meine Versuche endeten aber bisher mit verrauschten Bildern.

[MasterX]

Hier der Link zu einer Seite wo du dir den C-Source für Floy/Steinberg-Dithering saugen kannst.
Ist übrigens das FS-Plugin für GIMP; sollte also auch von der Qualität her nicht schlecht sein )

http://www.home.unix-ag.org/simon/gimp/fsdither.html

Grüße, MasterX

[MasterX]

Hab hier noch was für dich .... ist wahrscheinlich sogar besser - weil verständlicher, da es nicht plugin konzipiert ist.

/*
* dither -- use a reduced set of grey values to represent an image
*
* Copyright (C) 1988 by Dale Schumacher.
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose and without fee is hereby granted, provided
* that the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation. This software is provided "as is" without express or
* implied warranty.
*
*
* Notes:
*
* [1] Floyd-Steinberg dither:
* I should point out that the actual fractions we used were, assuming
* you are at X, moving left to right:
*
* X 7/16
* 3/16 5/16 1/16
*
* Note that the error goes to four neighbors, not three. I think this
* will probably do better (at least for black and white) than the
* 3/8-3/8-1/4 distribution, at the cost of greater processing. I have
* seen the 3/8-3/8-1/4 distribution described as "our" algorithm before,
* but I have no idea who the credit really belongs to.

* Also, I should add that if you do zig-zag scanning (see my immediately
* previous message), it is sufficient (but not quite as good) to send
* half the error one pixel ahead (e.g. to the right on lines you scan
* left to right), and half one pixel straight down. Again, this is for
* black and white; I've not tried it with color.
* --
* Lou Steinberg
*/

static char _Program[] = "dither";
static char _Version[] = "1.3";
static char _Copyright[] = "Copyright 1988 by Dale Schumacher";

#include <stdio.h>
#include <ctype.h>
#include "pxm.h"

#define DEBUG(x) if(0)/* x */

#define range 255 /* maximum pixel output value */

int levels = 2; /* number of output levels */

banner()
{
printf("%s v%s -- %s\n", _Program, _Version, _Copyright);
}

usage()
{
fprintf(stderr,
"usage: %s [-n levels] inpxm outpxm\n",
_Program);
exit(1);
}

main(argc, argv)
int argc;
char *argv[];
{
register PX_DEF *ipx, *opx;
FILE *f;
register int c;
register char *p;
extern int optind;
extern char *optarg;

while((c = getopt(argc, argv, "n:V")) != EOF)
{
switch(c)
{
case 'n':
levels = atoi(optarg);
break;
case 'V':
banner();
exit(0);
case '?':
default:
usage();
}
}
if((argc - optind) < 2)
usage();
else
{
ipx = px_ropen(argv[optind++]);
opx = px_wopen(argv[optind++],
(PXT_PIX | PXT_BIN),
ipx->px_width, ipx->px_height, 8, NULL);
dither(ipx, opx);
px_close(ipx);
px_close(opx);
}
exit(0);
}

dither(ipx, opx)
PX_DEF *ipx, *opx;
{
unsigned int xsize, ysize;
unsigned int y, x;
register int xslop, *yslop, dslop;
register int i, j, k, t, q;
register PX_BYTE *ibuf, *obuf;

xsize = ipx->px_width;
ysize = ipx->px_height;
ibuf = px_rowalloc(xsize, ipx->px_psize);
obuf = px_rowalloc(xsize, opx->px_psize);
yslop = (int *) px_alloc(xsize * sizeof(int));

t = ((range + 1) * 2) / levels; /* threshold factor */
q = range / (levels - 1); /* quantization factor */
j = (9 * range) / 32;
for(x=0; x<xsize; ++x)
yslop[x] = j;

for(y=0; y<ysize; ++y)
{
xslop = (7 * range) / 32;
dslop = range / 32;
px_rrow(ipx, ibuf);
for(x=0; x<xsize; ++x)
{
i = px_rgrey(ipx, ibuf, x);
i += xslop + yslop[x];
j = (i / t) * q;
if(j > range) /* quick hack to fix overflow */
j = range; /* which shouldn't happen */
px_wgrey(opx, obuf, x, j);
i = i - j;
k = (i >> 4); /* (i / 16) */
xslop = 7 * k;
yslop[x] = (5 * k) + dslop;
if(x > 0)
yslop[x-1] += 3 * k;
dslop = i - (15 * k);
}
px_wrow(opx, obuf);
}
}




P.S. nicht von mir !!!!!!!! ;o)

[LDIR]

Danke an Euch, ich muß es jetzt nur noch für Basic umschreiben und versuchen es in mein Programm einzubauen. mal sehen, hoffentlich klappt es... Etwas kompliziert das ganze!

[LDIR]

Da ich noch nie was mit C zu tun hatte, habe ich schwierigkeiten diese Routine zu Basic umzusetzen, kann mir bitte Jemand helfen?