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/*
* STV0680 Vision Camera Chipset Driver
* Copyright 2000 Adam Harrison <adam@antispin.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the
* Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*/
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include "bayer.h"
/* Enhanced by Kurt Garloff to do scaling and debayering at the same time. */
void bayer_unshuffle_preview(int w, int h, int scale, unsigned char *raw, unsigned char *output)
{
int x, y, nx, ny;
int colour; int rgb[3];
int nw = w >> scale;
int nh = h >> scale;
int incr = 1<<scale;
for (ny = 0; ny < nh; ++ny, raw += w<<scale) {
for (nx = 0; nx < nw; ++nx, output += 3) {
rgb[0] = 0; rgb[1] = 0; rgb[2] = 0;
for (y = 0; y < incr; ++y) {
for (x = 0; x < incr; ++x) {
colour = 1 - (x&1) + (y&1);
rgb[colour] += raw[y*w + (nx<<(scale-1))+(x>>1) + ((x&1)? 0: (w>>1))];
}
}
output[0] = rgb[0]>>(2*scale-2);
output[1] = rgb[1]>>(2*scale-1);
output[2] = rgb[2]>>(2*scale-2);
}
}
}
/****** gamma correction from trans[], plus hardcoded white balance */
/* Thanks to Alexander Schwartx <alexander.schwartx@gmx.net> for this code.
Gamma correction (trans[] values generated by (pow((i-17)/239, GAMMA)*254)
where GAMMA=0.5x, 1<i<255. */
/* KG: Looking at very dark parts of images, the sensor seems to produce
* only very few points below 0x11 and almost none below 14. Therefore we map everything
* below 14 to 0 and ev'thing below 17 to 1; then the power function reigns.
*/
#define ZERO0 14 /* 0--13 mapped to 0 */
#define ZERO1 17 /* 14--16 mapped to 1 */
typedef struct _rgbgamma {
float ampl, gamma;
} rgbgamma;
/* KG: Some notes on these:
* - Try to avoid strong deviations from 1.00 for the amplification,
* because this potentially results in not using the full range
* of colours (<1) or in clipping (>1) multiple colours to max,
* which would be a loss of information.
* - The gamma mainly determines how fast values increase after ZERO1.
* Influence on the highlights is small; therefore the description
* with amplifiaction and gamma seems not very appropriate; a better
* correction function would allow to influence the slope for small
* and for large values independently without incurring loss of
* accuracy/information. It should not be hard to construct such a
* thing. (Splines or Bézier or Triginometric/Hyperbolic functions
* could be used, e.g.)
* - The below parameters have been found by lots of experiments with
* pictures taken at different light levels. They're optimized for
* my PenCam (and my screens), of course. No theory behind this;
* I don't have insight into the physics of the imaging sensor.
* CCDs are linear, basically; but higher order effects may play
* a role as well as the electronics that controls the shutter
* and the one doing the readout.
*/
static const rgbgamma gampar[6][3] = {
{ { 1.02, 0.56 }, { 1.00, 0.61 }, { 0.99, 0.65 } }, /* cold */
{ { 1.01, 0.56 }, { 1.00, 0.58 }, { 1.00, 0.61 } }, /* coldish */
{ { 1.00, 0.55 }, { 1.00, 0.57 }, { 1.00, 0.59 } }, /* mid */
{ { 1.00, 0.55 }, { 1.00, 0.56 }, { 1.01, 0.55 } }, /* warmish */
{ { 1.01, 0.56 }, { 0.99, 0.57 }, { 1.03, 0.50 } }, /* warm */
{ { 1.03, 0.52 }, { 0.97, 0.57 }, { 1.04, 0.49 } } /* warm bright */
};
void light_enhance(int vw, int vh, int coarse, int fine,
unsigned char avg_pix, unsigned char *output)
{
unsigned long int i;
int lt=3; /* 3 is auto */
/* float wb[3][3]; */
unsigned char trans[3][256];
unsigned char col;
/* int tmp1, tmp2, tmp3, whitex=20, whitey=20, j, k; */
double brightness = 1.00; /* FIXME: configurable? */
/* fprintf(stderr, "(FineExp=%i CoarseExp=%i => filter=", fine, coarse); */
#if 0
if (fine >= (coarse<<1)) {
lt = 0;
/* fprintf(stderr, "natural)\n"); */
} else if (((fine<<1) < coarse) && (coarse < 400)) {
lt = 2;
/* fprintf(stderr, "incandescent)\n"); */
} else {
lt = 1;
/* fprintf(stderr, "fluorescent)\n"); */
}
wb[0][0] = 1.08 * x; wb[0][1] = 1.00 * x; wb[0][2] = 0.95 * x; /* natural */
wb[1][0] = 1.00 * x; wb[1][1] = 1.00 * x; wb[1][2] = 1.00 * x; /* fluorescent */
wb[2][0] = 0.90 * x; wb[2][1] = 1.00 * x; wb[2][2] = 1.11 * x; /* incandescent */
#else
if (fine > coarse) {
lt = 0; /* fprintf (stderr, "cold)\n"); */
} else if (coarse < 100) {
lt = 1; /* fprintf (stderr, "coldish)\n"); */
} else if (coarse < 200) {
lt = 2; /* fprintf (stderr, "mid)\n"); */
} else if (coarse < 400) {
lt = 3; /* fprintf (stderr, "warmish)\n"); */
} else if (avg_pix < 94) {
lt = 4; /* fprintf (stderr, "warm)\n"); */
} else {
lt = 5; /* fprintf (stderr, "warm, bright)\n"); */
}
#endif
#if 0
/* find white pixel */
for (j=0;j<vh;j++)
{
for (k=0; k<vw; k++)
{
i = (j*vw + k)*3;
tmp1 = abs(*(output+i) - *(output+i+1));
tmp2 = abs(*(output+i) - *(output+i+2));
tmp3 = abs(*(output+i+1) - *(output+i+2));
if ((tmp1<16) && (tmp2<16) && (tmp3<16) && (*(output+i)>=160)) {
whitex = k; whitey = j;
break;
}
}
}
#endif
for (col = 0; col < 3; col++) {
double y;
const rgbgamma *gp = gampar[lt] + col;
for(i=0; i<256; ++i) {
if (i < ZERO0)
y = 0;
else if (i < ZERO1)
y = 1;
else
y = brightness * gp->ampl * (2 + pow((i-ZERO1)/((double)254-ZERO1),gp->gamma) * 253.5);
if (y > 255.0)
y = 255.0;
trans[col][i] = (unsigned char) y;
}
}
for (i=0;i<(vw*vh*3);i+=3)
{
int r,g,b;
r = *(output+i);
g = *(output+i+1);
b = *(output+i+2);
/* this (adjusting white) isn't quite right yet, so I turned it off */
if ( 0 && (abs(r-g) < 8) &&
(abs(r-b) < 8) &&
(abs(b-g) < 8)) {
int v = trans[1][(r+b+g+1)/3];
*(output+i) = (unsigned char) (v);
*(output+i+1) = (unsigned char) (v);
*(output+i+2) = (unsigned char) (v);
fprintf(stderr,"Adjusting white\n");
} else { /* this is OK */
*(output+i) = trans[0][r];
*(output+i+1) = trans[1][g];
*(output+i+2) = trans[2][b];
}
} /* for */
} /* light_enhance */
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