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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.
*/
#include "video.h"
#include "dither.h"
/*
* We'll define the "ConvertColor" macro here to do fixed point arithmetic
* that'll convert from YCrCb to RGB using:
* R = L + 1.40200*Cr;
* G = L - 0.34414*Cb - 0.71414*Cr
* B = L + 1.77200*Cb;
*
* We'll use fixed point by adding two extra bits after the decimal.
*/
#define BITS 8
#define ONE ((int) 1)
#define CONST_SCALE (ONE << BITS)
#define ROUND_FACTOR (ONE << (BITS-1))
/* Macro to convert integer to fixed. */
#define UP(x) (((int)(x)) << BITS)
/* Macro to convert fixed to integer (with rounding). */
#define DOWN(x) (((x) + ROUND_FACTOR) >> BITS)
/* Macro to convert a float to a fixed */
#define FIX(x) ((int) ((x)*CONST_SCALE + 0.5))
#define CLAMP(ll,x,ul) ( ((x)<(ll)) ?(ll):( ((x)>(ul)) ?(ul):(x)))
static int *Cb_r_tab, *Cr_g_tab, *Cb_g_tab, *Cr_b_tab;
/*
*--------------------------------------------------------------
*
* InitColorDither --
*
* To get rid of the multiply and other conversions in color
* dither, we use a lookup table.
*
* Results:
* None.
*
* Side effects:
* The lookup tables are initialized.
*
*--------------------------------------------------------------
*/
void
InitColorDither()
{
int CR, CB, i;
Cr_b_tab = (int *)malloc(256*sizeof(int));
Cr_g_tab = (int *)malloc(256*sizeof(int));
Cb_g_tab = (int *)malloc(256*sizeof(int));
Cb_r_tab = (int *)malloc(256*sizeof(int));
for (i=0; i<256; i++) {
CB = CR = i;
CB -= 128; CR -= 128;
Cb_r_tab[i] = FIX(1.40200) * CB;
Cr_g_tab[i] = -FIX(0.34414) * CR;
Cb_g_tab[i] = -FIX(0.71414) * CB;
Cr_b_tab[i] = FIX(1.77200) * CR;
}
}
/*
*--------------------------------------------------------------
*
* ColorDitherImage --
*
* Converts image into 24 bit color.
*
* Results:
* None.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
void
ColorDitherImage(lum, cr, cb, out, rows, cols)
unsigned char *lum;
unsigned char *cr;
unsigned char *cb;
unsigned char *out;
int cols, rows;
{
int L, CR, CB;
unsigned char *row1, *row2;
unsigned char *lum2;
int x, y, colsT3;
unsigned int r, b, g;
int cb_r, cr_g, cb_g, cr_b, R, G, B;
row1 = out;
colsT3 = 3 * cols;
row2 = row1 + colsT3;
lum2 = lum + cols;
for (y=0; y<rows; y+=2) {
for (x=0; x<cols; x+=2) {
cb_r = Cb_r_tab[*cb];
cr_g = Cr_g_tab[*cr];
cb_g = Cb_g_tab[*cb++];
cr_b = Cr_b_tab[*cr++];
L = UP(*lum++);
R = (L + cb_r)>>BITS;
G = (L + cr_g + cb_g)>>BITS;
B = (L + cr_b)>>BITS;
*row1++ = CLAMP(0,R,255);
*row1++ = CLAMP(0,G,255);
*row1++ = CLAMP(0,B,255);
L = UP(*lum++);
R = (L + cb_r)>>BITS;
G = (L + cr_g + cb_g)>>BITS;
B = (L + cr_b)>>BITS;
*row1++ = CLAMP(0,R,255);
*row1++ = CLAMP(0,G,255);
*row1++ = CLAMP(0,B,255);
/* Now, do second row */
L = UP(*lum2++);
R = (L + cb_r)>>BITS;
G = (L + cr_g + cb_g)>>BITS;
B = (L + cr_b)>>BITS;
*row2++ = CLAMP(0,R,255);
*row2++ = CLAMP(0,G,255);
*row2++ = CLAMP(0,B,255);
L = UP(*lum2++);
R = (L + cb_r)>>BITS;
G = (L + cr_g + cb_g)>>BITS;
B = (L + cr_b)>>BITS;
*row2++ = CLAMP(0,R,255);
*row2++ = CLAMP(0,G,255);
*row2++ = CLAMP(0,B,255);
}
lum += cols;
lum2 += cols;
row1 += colsT3;
row2 += colsT3;
}
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.