aptdec/image.c

/*
 *  Atpdec
 *  Copyright (c) 2004 by Thierry Leconte (F4DWV)
 *
 *      $Id$
 *
 *   This library 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; 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 Library General Public License for more details.
 *
 *   You should have received a copy of the GNU Library General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <stdio.h>
#include <string.h>
#include <sndfile.h>
#include <math.h>

#include "offsets.h"

#define REGORDER 3
typedef struct {
    double cf[REGORDER + 1];
} rgparam;

static void rgcomp(double x[16], rgparam * rgpr)
{
/*{ 0.106,0.215,0.324,0.433,0.542,0.652,0.78,0.87 ,0.0 }; */
    const double y[9] =
	{ 31.07, 63.02, 94.96, 126.9, 158.86, 191.1, 228.62, 255.0, 0.0 };
    extern void polyreg(const int m, const int n, const double x[],
			const double y[], double c[]);

    polyreg(REGORDER, 9, x, y, rgpr->cf);
}

static double rgcal(float x, rgparam * rgpr)
{
    double y, p;
    int i;

    for (i = 0, y = 0.0, p = 1.0; i < REGORDER + 1; i++) {
	y += rgpr->cf[i] * p;
	p = p * x;
    }
    return (y);
}


static double tele[16];
static double Cs;
static int nbtele;

int Calibrate(float **prow, int nrow, int offset)
{

    double teleline[3000];
    double wedge[16];
    rgparam regr[30];
    int n;
    int k;
    int mtelestart, telestart;
    int channel = -1;
    float max;

    printf("Calibration ... ");
    fflush(stdout);

/* build telemetry values lines */
    for (n = 0; n < nrow; n++) {
	int i;

	teleline[n] = 0.0;
	for (i = 3; i < 43; i++) {
	    teleline[n] += prow[n][i + offset + CH_WIDTH];
	}
	teleline[n] /= 40.0;
    }

    if (nrow < 192) {
	fprintf(stderr, " impossible, not enought row\n");
	return (0);
    }

/* find telemetry start in the 2nd third */
    max = 0.0;
    mtelestart = 0;
    for (n = nrow / 3 - 64; n < 2 * nrow / 3 - 64; n++) {
	float df;

	df = (teleline[n - 4] + teleline[n - 3] + teleline[n - 2] +
	      teleline[n - 1]) / (teleline[n] + teleline[n + 1] +
				  teleline[n + 2] + teleline[n + 3]);
	if (df > max) {
	    mtelestart = n;
	    max = df;
	}
    }

    mtelestart -= 64;
    telestart = mtelestart % 128;

    if (mtelestart < 0 || nrow < telestart + 128) {
	fprintf(stderr, " impossible, not enought row\n");
	return (0);
    }

/* compute wedges and regression */
    for (n = telestart, k = 0; n < nrow - 128; n += 128, k++) {
	int j;

	for (j = 0; j < 16; j++) {
	    int i;

	    wedge[j] = 0.0;
	    for (i = 1; i < 7; i++)
		wedge[j] += teleline[n + j * 8 + i];
	    wedge[j] /= 6;
	}

	rgcomp(wedge, &(regr[k]));

	if (k == nrow / 256) {
	    int i, l;

	    /* telemetry calibration */
	    for (j = 0; j < 16; j++) {
		tele[j] = rgcal(wedge[j], &(regr[k]));
	    }


	    /* channel ID */
	    for (j = 0, max = 10000.0, channel = -1; j < 6; j++) {
		float df;

		df = wedge[15] - wedge[j];
		df = df * df;
		if (df < max) {
		    channel = j;
		    max = df;
		}
	    }

	    /* Cs computation */
	    for (Cs = 0.0, i = 0, j = n; j < n + 128; j++) {
		double csline;

		for (csline = 0.0, l = 3; l < 43; l++)
		    csline += prow[n][l + offset -SPC_WIDTH];
		csline /= 40.0;
		if (csline > 50.0) {
		    Cs += csline;
		    i++;
		}
	    }
	    Cs /= i;
	    Cs = rgcal(Cs, &(regr[k]));
	}
    }
    nbtele = k;

/* calibrate */
    for (n = 0; n < nrow; n++) {
	float *pixelv;
	int i;

	pixelv = prow[n];
	for (i = 0; i < CH_WIDTH; i++) {
	    float pv;
	    int k, kof;

	    pv = pixelv[i + offset];

	    k = (n - telestart) / 128;
	    if (k >= nbtele)
		k = nbtele - 1;
	    kof = (n - telestart) % 128;
	    if (kof < 64) {
		if (k < 1) {
		    pv = rgcal(pv, &(regr[k]));
		} else {
		    pv = rgcal(pv, &(regr[k])) * (64 + kof) / 128.0 +
			rgcal(pv, &(regr[k - 1])) * (64 - kof) / 128.0;
		}
	    } else {
		if ((k + 1) >= nbtele) {
		    pv = rgcal(pv, &(regr[k]));
		} else {
		    pv = rgcal(pv, &(regr[k])) * (192 - kof) / 128.0 +
			rgcal(pv, &(regr[k + 1])) * (kof - 64) / 128.0;
		}
	    }

	    if (pv > 255.0)
		pv = 255.0;
	    if (pv < 0.0)
		pv = 0.0;
	    pixelv[i + offset] = pv;
	}
    }
    printf("Done\n");
    return (channel+1);
}

/* ------------------------------temperature calibration -----------------------*/
extern int satnum;
#include "satcal.h"

typedef struct {
    double Nbb;
    double Cs;
    double Cb;
    int ch;
} tempparam;

/* temperature compensation for IR channel */
static void tempcomp(double t[16], int ch, tempparam * tpr)
{
    double Tbb, T[4];
    double C;
    int n;

    tpr->ch = ch - 4;

    /* compute equivalent T black body  */
    for (n = 0; n < 4; n++) {
	float d0, d1, d2;

	C = t[9 + n] * 4.0;
	d0 = satcal[satnum].d[n][0];
	d1 = satcal[satnum].d[n][1];
	d2 = satcal[satnum].d[n][2];
	T[n] = d0;
	T[n] += d1 * C;
	C = C * C;
	T[n] += d2 * C;
    }
    Tbb = (T[0] + T[1] + T[2] + T[3]) / 4.0;
    Tbb =
	satcal[satnum].rad[tpr->ch].A +
	satcal[satnum].rad[tpr->ch].B * Tbb;

    /* compute radiance Black body */
    C = satcal[satnum].rad[tpr->ch].vc;
    tpr->Nbb = c1 * C * C * C / (exp(c2 * C / Tbb) - 1.0);
    /* store Count Blackbody and space */
    tpr->Cs = Cs * 4.0;
    tpr->Cb = t[14] * 4.0;
}

static double tempcal(float Ce, tempparam * rgpr)
{
    double Nl, Nc, Ns, Ne;
    double T, vc;

    Ns = satcal[satnum].cor[rgpr->ch].Ns;
    Nl = Ns + (rgpr->Nbb - Ns) * (rgpr->Cs - Ce * 4.0) / (rgpr->Cs -
							  rgpr->Cb);
    Nc = satcal[satnum].cor[rgpr->ch].b[0] +
	satcal[satnum].cor[rgpr->ch].b[1] * Nl +
	satcal[satnum].cor[rgpr->ch].b[2] * Nl * Nl;

    Ne = Nl + Nc;

    vc = satcal[satnum].rad[rgpr->ch].vc;
    T = c2 * vc / log(c1 * vc * vc * vc / Ne + 1.0);
    T = (T - satcal[satnum].rad[rgpr->ch].A) / satcal[satnum].rad[rgpr->ch].B;

    /* rescale to range 0-255 for -60 +40 °C */
    T = (T - 273.15 + 60.0) / 100.0 * 256.0;

    return (T);
}

void Temperature(float **prow, int nrow, int channel, int offset)
{
    tempparam temp;
    int n;

    printf("Temperature ... ");
    fflush(stdout);

    tempcomp(tele, channel, &temp);

    for (n = 0; n < nrow; n++) {
	float *pixelv;
	int i;

	pixelv = prow[n];
	for (i = 0; i < CH_WIDTH; i++) {
	    float pv;

	    pv = tempcal(pixelv[i + offset], &temp);

	    if (pv > 255.0)
		pv = 255.0;
	    if (pv < 0.0)
		pv = 0.0;
	    pixelv[i + offset] = pv;
	}
    }
    printf("Done\n");
}