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/*
colorTables for 8 Bit depth
Copyright (C) 2000 Martin Vogt
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published by
the Free Software Foundation.
For more information look at the file COPYRIGHT in this package
*/
#include "colorTable8Bit.h"
ColorTable8Bit::ColorTable8Bit() {
lum_values = new int[LUM_RANGE];
cr_values = new int[CR_RANGE];
cb_values = new int[CB_RANGE];
/* We can exploit cache by allocating contiguous blocks */
colortab = new TABTYPE[5*256];
Cr_r_tab = &colortab[0*256];
Cr_g_tab = &colortab[1*256];
Cb_g_tab = &colortab[2*256];
Cb_b_tab = &colortab[3*256];
L_tab = &colortab[4*256];
init8BitColor();
}
ColorTable8Bit::~ColorTable8Bit() {
delete lum_values;
delete cr_values;
delete cb_values;
delete colortab;
}
void ColorTable8Bit::init8BitColor() {
int i;
for (i=0; i<LUM_RANGE; i++) {
lum_values[i] = ((i * 256) / (LUM_RANGE)) + (256/(LUM_RANGE*2));
L_tab[i] = lum_values[i];
if (gammaCorrectFlag) {
L_tab[i] = GAMMA_CORRECTION(L_tab[i]);
}
}
for (i=0; i<CR_RANGE; i++) {
double tmp;
if (chromaCorrectFlag) {
tmp = ((i * 256) / (CR_RANGE)) + (256/(CR_RANGE*2));
Cr_r_tab[i]=(TABTYPE) ((0.419/0.299)*CHROMA_CORRECTION128D(tmp-128.0));
Cr_g_tab[i]=(TABTYPE) (-(0.299/0.419)*CHROMA_CORRECTION128D(tmp-128.0));
cr_values[i] = CHROMA_CORRECTION256(tmp);
} else {
tmp = ((i * 256) / (CR_RANGE)) + (256/(CR_RANGE*2));
Cr_r_tab[i] = (TABTYPE) ((0.419/0.299) * (tmp - 128.0));
Cr_g_tab[i] = (TABTYPE) (-(0.299/0.419) * (tmp - 128.0));
cr_values[i] = (int) tmp;
}
}
for (i=0; i<CB_RANGE; i++) {
double tmp;
if (chromaCorrectFlag) {
tmp = ((i * 256) / (CB_RANGE)) + (256/(CB_RANGE*2));
Cb_g_tab[i]=(TABTYPE) (-(0.114/0.331)*CHROMA_CORRECTION128D(tmp-128.0));
Cb_b_tab[i]=(TABTYPE) ((0.587/0.331)*CHROMA_CORRECTION128D(tmp-128.0));
cb_values[i] = CHROMA_CORRECTION256(tmp);
} else {
tmp = ((i * 256) / (CB_RANGE)) + (256/(CB_RANGE*2));
Cb_g_tab[i] = (TABTYPE) (-(0.114/0.331) * (tmp - 128.0));
Cb_b_tab[i] = (TABTYPE) ((0.587/0.331) * (tmp - 128.0));
cb_values[i] = (int) tmp;
}
}
}
/*
*--------------------------------------------------------------
*
* ConvertColor --
*
* Given a l, cr, cb tuple, converts it to r,g,b.
*
* Results:
* r,g,b values returned in pointers passed as parameters.
*
* Side effects:
* None.
*
*--------------------------------------------------------------
*/
void ColorTable8Bit::ConvertColor(unsigned int l, unsigned int cr,
unsigned int cb, unsigned char* r,
unsigned char* g, unsigned char* b) {
double fl, fr, fg, fb;
/*
* Old method w/o lookup table
*
* fl = 1.164*(((double) l)-16.0);
* fcr = ((double) cr) - 128.0;
* fcb = ((double) cb) - 128.0;
*
* fr = fl + (1.366 * fcr);
* fg = fl - (0.700 * fcr) - (0.334 * fcb);
* fb = fl + (1.732 * fcb);
*/
fl = L_tab[l];
fr = fl + Cr_r_tab[cr];
fg = fl + Cr_g_tab[cr] + Cb_g_tab[cb];
fb = fl + Cb_b_tab[cb];
if (fr < 0.0) fr = 0.0;
else if (fr > 255.0) fr = 255.0;
if (fg < 0.0) fg = 0.0;
else if (fg > 255.0) fg = 255.0;
if (fb < 0.0) fb = 0.0;
else if (fb > 255.0) fb = 255.0;
*r = (unsigned char) fr;
*g = (unsigned char) fg;
*b = (unsigned char) fb;
}
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