/*
 				weight.c

*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*
*	Part of:	SExtractor
*
*	Author:		E.BERTIN (IAP)
*
*	Contents:	Handling of weight maps.
*
*	Last modify:	28/11/2003
*
*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
*/

#ifdef HAVE_CONFIG_H
#include        "config.h"
#endif

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

#include	"define.h"
#include	"globals.h"
#include	"field.h"
#include	"weight.h"

/******************************* newweight **********************************/
/*
Load a weight map and initialize relevant parameters.
*/
picstruct	*newweight(char *filename, picstruct *reffield,
			weightenum wtype, int nok)

  {
   picstruct	*wfield;

  switch(wtype)
    {
    case WEIGHT_FROMINTERP:
      wfield = inheritfield(reffield, INTERP_FIELD);
      break;

    case WEIGHT_FROMBACK:
      wfield = inheritfield(reffield, BACKRMS_FIELD);
      break;

    case WEIGHT_FROMRMSMAP:
      wfield = newfield(filename, RMS_FIELD, nok);
      if ((wfield->width!=reffield->width)||(wfield->height!=reffield->height))
        error(EXIT_FAILURE,
	"*Error*: measured frame and weight map have different sizes","");
      wfield->sigfac = 1.0;
      break;

    case WEIGHT_FROMVARMAP:
      wfield = newfield(filename, VAR_FIELD, nok);
      if ((wfield->width!=reffield->width)||(wfield->height!=reffield->height))
        error(EXIT_FAILURE,
	"*Error*: measured frame and weight map have different sizes","");
      break;

    case WEIGHT_FROMWEIGHTMAP:
      wfield = newfield(filename, WEIGHT_FIELD, nok);
      if ((wfield->width!=reffield->width)||(wfield->height!=reffield->height))
        error(EXIT_FAILURE,
	"*Error*: measured frame and weight map have different sizes","");
      break;
    default:
      wfield = NULL;			/* To avoid gcc -Wall warnings */
      error(EXIT_FAILURE,
	"*Internal Error*: Unknown weight-map type in ", "makeit()");
      break;
    }

/* Default normalization factor (will be changed if necessary later) */
  wfield->sigfac = 1.0;

  return wfield;
  }


/******************************* weight_to_var *******************************/
/*
Transform an array of possibily unnormalized weights into a calibrated
variance map.
*/
void	weight_to_var(picstruct *wfield, PIXTYPE *data, int npix)

  {
   float	sigfac2;
   int		i;

  switch(wfield->flags&(BACKRMS_FIELD|RMS_FIELD|VAR_FIELD|WEIGHT_FIELD))
    {
    case BACKRMS_FIELD:
    case RMS_FIELD:
      for (i=npix; i--; data++)
        if (*data<BIG)
          *data *= *data;
      break;
    case VAR_FIELD:
      sigfac2 = wfield->sigfac*wfield->sigfac;
      for (i=npix; i--;)
        *(data++) *= sigfac2;
      break;
    case WEIGHT_FIELD:
     sigfac2 = wfield->sigfac*wfield->sigfac;
     for (i=npix; i--; data++)
      if (*data > 0.0)
        *data = sigfac2/(*data);
      else
        *data = BIG;
      break;
    default:
      error(EXIT_FAILURE,
	"*Internal Error*: Unknown weight-map type in ", "weight_to_var()");
      break;
    }

  return;
  }