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/*
* Author: Yoichiro Ueno (ueno@cs.titech.ac.jp)
*
* Copyright (C) 1991, 1992, Yoichiro Ueno.
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose is hereby granted by the Author without
* fee, provided that the above copyright notice appear in all copies and
* that both the copyright notice and this permission notice appear in
* supporting documentation, and that the name of the Author not be used
* in advertising or publicity pertaining to distribution of the software
* without specific, written prior permission. The Author makes no
* representations about the suitability of this software for any purpose.
* It is provided "as is" without express or implied warranty.
*
* THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*
*/
#include "video.h"
#include "proto.h"
#include "dither.h"
/*
*--------------------------------------------------------------
*
* MonoDitherImage --
*
* Dithers image into monochrome.
* Dither algorithm is based on dither.c in xli.1.11.
*
* Results:
* None.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
#define MaxGrey 65280
#define Threshold (MaxGrey/2)
#define MinGrey 0
#if ultrix && mips
# define SEED_BIT 0x01
# define OPP_SEED_BIT 0x80
# define SHIFT_SEED_BIT(b) (b <<= 1)
# define OPP_SHIFT_SEED_BIT(b) (b >>= 1)
#else
# define SEED_BIT 0x80
# define OPP_SEED_BIT 0x01
# define SHIFT_SEED_BIT(b) (b >>= 1)
# define OPP_SHIFT_SEED_BIT(b) (b <<= 1)
#endif
static int *curr = NULL;
static int *next = NULL;
void
MonoDitherImage(lum, cr, cb, out, h, w)
register unsigned char *lum;
unsigned char *cr;
unsigned char *cb;
register unsigned char *out;
int w, h;
{
int bit_r2l;
register unsigned int bit;
register unsigned int data;
int i;
register int j;
int *swap;
register int out_err;
register int next1;
register int next2;
if(curr == NULL) {
curr = (int *)malloc(sizeof(int) * (w + 2));
curr += 1;
}
if(next == NULL) {
next = (int *)malloc(sizeof(int) * (w + 2));
next += 1;
}
bzero ((char *)curr, w * sizeof(*curr));
bit_r2l = SEED_BIT << (w - 1 & 7);
for(i = 0; i < h; i ++) {
if(i & 0x01) { /* Right to Left */
bit = bit_r2l;
data = 0;
out_err = curr[w-1];
next1 = 0;
next2 = 0;
for (j=(w-1); j>=0; j--)
{
out_err = (out_err >> 4) + (lum[j] << 8);
if(out_err > Threshold) {
data |= bit;
out_err -= MaxGrey;
}
else
out_err -= MinGrey;
next[j+1] = next1 + (out_err * 3);
next1 = next2 + (out_err * 5);
next2 = (out_err * 1);
out_err = curr[j-1] + (out_err * 7);
OPP_SHIFT_SEED_BIT(bit);
#if ultrix && mips
if(bit == 0) {
#else
if(bit > 0x80) {
#endif
out[j >> 3] = data;
bit = OPP_SEED_BIT;
data = 0;
}
}
next[0] = next1;
}
else { /* Left to Right */
bit = SEED_BIT;
data = 0;
out_err = curr[0];
next1 = 0;
next2 = 0;
for (j=0; j<w; j++)
{
out_err = (out_err >> 4) + (lum[j] << 8);
if(out_err > Threshold) {
data |= bit;
out_err = out_err - MaxGrey;
}
else
out_err = out_err - MinGrey;
next[j-1] = next1 + (out_err * 3);
next1 = next2 + (out_err * 5);
next2 = (out_err * 1);
out_err = curr[j+1] + (out_err * 7);
SHIFT_SEED_BIT(bit);
#if ultrix && mips
if(bit > 0x80) {
#else
if(bit == 0) {
#endif
out[j >> 3] = data;
bit = SEED_BIT;
data = 0;
}
}
next[w-1] = next1;
}
lum += w;
out += w >> 3;
swap = curr;
curr = next;
next = swap;
}
}
/*
*--------------------------------------------------------------
*
* MonoThresholdImage --
*
* convert image into monochrome with threshold.
*
* Results:
* None.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
void
MonoThresholdImage(lum, cr, cb, out, h, w)
unsigned char *lum;
unsigned char *cr;
unsigned char *cb;
unsigned char *out;
int w, h;
{
unsigned char bit;
unsigned char data;
bit = SEED_BIT;
data = 0;
for (w*=h; w>0; w--) {
if(*lum++>128)
data |= bit;
SHIFT_SEED_BIT(bit);
if(bit == 0) {
*out ++ = data;
bit = SEED_BIT;
data = 0;
}
}
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.