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/*
* Copyright (c) 1992 The Regents of the University of California.
* All rights reserved.
*
* Permission to use, copy, modify, and distribute this software and its
* documentation for any purpose, without fee, and without written agreement is
* hereby granted, provided that the above copyright notice and the following
* two paragraphs appear in all copies of this software.
*
* IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT
* OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF
* CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
* ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*/
/* This file contains C code to implement an ordered dither. */
#include <config.h>
#include "video.h"
#include "proto.h"
#include "dither.h"
#define DITH_SIZE 16
/* Structures used to implement hybrid ordered dither/floyd-steinberg
dither algorithm.
*/
static unsigned char *l_darrays[DITH_SIZE];
static unsigned char *cr_darrays[DITH_SIZE];
static unsigned char *cb_darrays[DITH_SIZE];
/*
*--------------------------------------------------------------
*
* InitOrderedDither--
*
* Structures intialized for ordered dithering.
*
* Results:
* None.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
void
InitOrderedDither()
{
int i, j, k, err_range, threshval;
unsigned char *lmark, *cmark;
for (i=0; i<DITH_SIZE; i++) {
lmark = l_darrays[i] = (unsigned char *) malloc(256);
for (j=0; j<lum_values[0]; j++) {
*lmark++ = 0;
}
for (j=0; j<(LUM_RANGE-1); j++) {
err_range = lum_values[j+1] - lum_values[j];
threshval = ((i * err_range) / DITH_SIZE)+lum_values[j];
for (k=lum_values[j]; k<lum_values[j+1]; k++) {
if (k > threshval) *lmark++ = ((j+1) * (CR_RANGE * CB_RANGE));
else *lmark++ = (j * (CR_RANGE * CB_RANGE));
}
}
for (j=lum_values[LUM_RANGE-1]; j<256; j++) {
*lmark++ = (LUM_RANGE-1)*(CR_RANGE * CB_RANGE);
}
}
for (i=0; i<DITH_SIZE; i++) {
cmark = cr_darrays[i] = (unsigned char *) malloc(256);
for (j=0; j<cr_values[0]; j++) {
*cmark++ = 0;
}
for (j=0; j<(CR_RANGE-1); j++) {
err_range = cr_values[j+1] - cr_values[j];
threshval = ((i * err_range) / DITH_SIZE)+cr_values[j];
for (k=cr_values[j]; k<cr_values[j+1]; k++) {
if (k > threshval) *cmark++ = ((j+1) * CB_RANGE);
else *cmark++ = (j * CB_RANGE);
}
}
for (j=cr_values[CR_RANGE-1]; j<256; j++) {
*cmark++ = (CR_RANGE-1)*(CB_RANGE);
}
}
for (i=0; i<DITH_SIZE; i++) {
cmark = cb_darrays[i] = (unsigned char *) malloc(256);
for (j=0; j<cb_values[0]; j++) {
*cmark++ = 0;
}
for (j=0; j<(CB_RANGE-1); j++) {
err_range = cb_values[j+1] - cb_values[j];
threshval = ((i * err_range) / DITH_SIZE)+cb_values[j];
for (k=cb_values[j]; k<cb_values[j+1]; k++) {
if (k > threshval) *cmark++ = j+1;
else *cmark++ = j;
}
}
for (j=cb_values[CB_RANGE-1]; j<256; j++) {
*cmark++ = CB_RANGE-1;
}
}
}
/*
*--------------------------------------------------------------
*
* OrderedDitherImage --
*
* Dithers an image using an ordered dither.
* Assumptions made:
* 1) The color space is allocated y:cr:cb = 8:4:4
* 2) The spatial resolution of y:cr:cb is 4:1:1
* The channels are dithered based on the standard
* ordered dither pattern for a 4x4 area.
*
* Results:
* None.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
void
OrderedDitherImage (lum, cr, cb, out, h, w)
unsigned char *lum;
unsigned char *cr;
unsigned char *cb;
unsigned char *out;
int w, h;
{
unsigned char *l, *r, *b, *o1, *o2;
unsigned char *l2;
unsigned char L, R, B;
int i, j;
l = lum;
l2 = lum+w;
r = cr;
b = cb;
o1 = out;
o2 = out+w;
for (i=0; i<h; i+=4) {
for (j=0; j<w; j+=8) {
R = r[0]; B = b[0];
L = l[0];
o1[0] = pixel[(l_darrays[0][L] + cr_darrays[0][R] + cb_darrays[0][B])];
L = l[1];
o1[1] = pixel[(l_darrays[8][L] + cr_darrays[8][R] + cb_darrays[8][B])];
L = l2[0];
o2[0] = pixel[(l_darrays[12][L] + cr_darrays[12][R] + cb_darrays[12][B])];
L = l2[1];
o2[1] = pixel[(l_darrays[4][L] + cr_darrays[4][R] + cb_darrays[4][B])];
R = r[1]; B = b[1];
L = l[2];
o1[2] = pixel[(l_darrays[2][L] + cr_darrays[2][R] + cb_darrays[2][B])];
L = l[3];
o1[3] = pixel[(l_darrays[10][L] + cr_darrays[10][R] + cb_darrays[10][B])];
L = l2[2];
o2[2] = pixel[(l_darrays[14][L] + cr_darrays[14][R] + cb_darrays[14][B])];
L = l2[3];
o2[3] = pixel[(l_darrays[6][L] + cr_darrays[6][R] + cb_darrays[6][B])];
R = r[2]; B = b[2];
L = l[4];
o1[4] = pixel[(l_darrays[0][L] + cr_darrays[0][R] + cb_darrays[0][B])];
L = l[5];
o1[5] = pixel[(l_darrays[8][L] + cr_darrays[8][R] + cb_darrays[8][B])];
L = l2[4];
o2[4] = pixel[(l_darrays[12][L] + cr_darrays[12][R] + cb_darrays[12][B])];
L = l2[5];
o2[5] = pixel[(l_darrays[4][L] + cr_darrays[4][R] + cb_darrays[4][B])];
R = r[3]; B = b[3];
L = l[6];
o1[6] = pixel[(l_darrays[2][L] + cr_darrays[2][R] + cb_darrays[2][B])];
L = l[7];
o1[7] = pixel[(l_darrays[10][L] + cr_darrays[10][R] + cb_darrays[10][B])];
L = l2[6];
o2[6] = pixel[(l_darrays[14][L] + cr_darrays[14][R] + cb_darrays[14][B])];
L = l2[7];
o2[7] = pixel[(l_darrays[6][L] + cr_darrays[6][R] + cb_darrays[6][B])];
l += 8;
l2 += 8;
r += 4;
b += 4;
o1 += 8;
o2 += 8;
}
l += w; l2 += w;
o1 += w; o2 += w;
for (j=0; j<w; j+=8) {
R = r[0]; B = b[0];
L = l[0];
o1[0] = pixel[(l_darrays[3][L] + cr_darrays[3][R] + cb_darrays[3][B])];
L = l[1];
o1[1] = pixel[(l_darrays[11][L] + cr_darrays[11][R] + cb_darrays[11][B])];
L = l2[0];
o2[0] = pixel[(l_darrays[15][L] + cr_darrays[15][R] + cb_darrays[15][B])];
L = l2[1];
o2[1] = pixel[(l_darrays[7][L] + cr_darrays[7][R] + cb_darrays[7][B])];
R = r[1]; B = b[1];
L = l[2];
o1[2] = pixel[(l_darrays[1][L] + cr_darrays[1][R] + cb_darrays[1][B])];
L = l[3];
o1[3] = pixel[(l_darrays[9][L] + cr_darrays[9][R] + cb_darrays[9][B])];
L = l2[2];
o2[2] = pixel[(l_darrays[13][L] + cr_darrays[13][R] + cb_darrays[13][B])];
L = l2[3];
o2[3] = pixel[(l_darrays[5][L] + cr_darrays[5][R] + cb_darrays[5][B])];
R = r[2]; B = b[2];
L = l[4];
o1[4] = pixel[(l_darrays[3][L] + cr_darrays[3][R] + cb_darrays[3][B])];
L = l[5];
o1[5] = pixel[(l_darrays[11][L] + cr_darrays[11][R] + cb_darrays[11][B])];
L = l2[4];
o2[4] = pixel[(l_darrays[15][L] + cr_darrays[15][R] + cb_darrays[15][B])];
L = l2[5];
o2[5] = pixel[(l_darrays[7][L] + cr_darrays[7][R] + cb_darrays[7][B])];
R = r[3]; B = b[3];
L = l[6];
o1[6] = pixel[(l_darrays[1][L] + cr_darrays[1][R] + cb_darrays[1][B])];
L = l[7];
o1[7] = pixel[(l_darrays[9][L] + cr_darrays[9][R] + cb_darrays[9][B])];
L = l2[6];
o2[6] = pixel[(l_darrays[13][L] + cr_darrays[13][R] + cb_darrays[13][B])];
L = l2[7];
o2[7] = pixel[(l_darrays[5][L] + cr_darrays[5][R] + cb_darrays[5][B])];
l += 8;
l2 += 8;
r += 4;
b += 4;
o1 += 8;
o2 += 8;
}
l += w; l2 += w;
o1 += w; o2 += w;
}
}
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