mrprior.c File Reference

Median Root Prior. More...

#include "libtpcrec.h"

Go to the source code of this file.

Functions
float	med9 (float *inp, int dim)
float	med21 (float *inp, int dim)
void	do_prior (float *img, float beta, float *med_coef, int dim, float small, int maskdim, float *maxm)

Detailed Description

Median Root Prior.

Based on the program fbprec (Feb 1998) written by Sakari Alenius for Sun UNIX workstations.

Author

Vesa Oikonen

Definition in file mrprior.c.

Function Documentation

do_prior()

void do_prior	(	float *	img,
		float	beta,
		float *	med_coef,
		int	dim,
		float	small,
		int	maskdim,
		float *	maxm )

Do prior in MRP reconstruction.

Parameters

img	Float array of size dim*dim containing the image data.
beta	Beta value.
med_coef	Median coefficients, an array of size dim*dim, calculated here.
dim	Image dimensions.
small	Limit for too small values.
maskdim	Mask dimensions; 3 or 5.
maxm	Max median coefficient; enter NULL if not needed.

Definition at line 77 of file mrprior.c.

  {
  int i, j;
  float *iptr, *mptr, med, f, mmax=0.0;
  float one_minus_beta=1.0-beta;
 
  //printf("do_prior(%d, %d)\n", dim, maskdim); fflush(stdout);
  for(i=0; i<dim*dim; i++) med_coef[i]=0.0;
 
  if(maskdim==3) {
    iptr=img+dim+1;
    mptr=med_coef+dim+1;
    for(j=1; j<dim-1; j++) {
      for(i=1; i<dim-1; i++) {
        if(*iptr<=small) {
          *mptr=0.0;
        } else {
          med=med9(iptr, dim);
          if(med==0.0) {
            *mptr=0.0;
          } else {
            f=med/(beta*(*iptr) + one_minus_beta*med);
            if(f>1.0E-08) *mptr=f; else *mptr=0.0;
          }
        }
        if(*mptr>mmax) mmax=*mptr;
        iptr++; mptr++;
      }
      iptr+=2; mptr+=2;
    }
    if(maxm!=NULL) *maxm=mmax;
    //printf("out from do_prior()\n"); fflush(stdout);
    return;
  }
 
  if(maskdim==5) {
    iptr=img+2*dim+2;
    mptr=med_coef+2*dim+2;
    for(j=2; j<dim-2; j++) {
      for(i=2; i<dim-2; i++) {
        if(*iptr<=small) {
          *mptr=0.0;
        } else {
          med=med21(iptr, dim);
          if(med==0.0) {
            *mptr=0.0;
          } else {
            f=med/(beta*(*iptr) + one_minus_beta*med);
            if(f>1.0E-08) *mptr=f; else *mptr=0.0;
          }
        }
        if(*mptr>mmax) mmax=*mptr;
        iptr++; mptr++;
      }
      iptr+=4; mptr+=4;
    }
    if(maxm!=NULL) *maxm=mmax;
    //printf("out from do_prior()\n"); fflush(stdout);
    return;
  }
}

Referenced by mrp(), and trmrp().

med21()

float med21	(	float *	inp,
		int	dim )

Compute 5x5 median without corners from image data inside float array.

Returns

Returns the median value.

Parameters

inp	Pointer to central pixel in image data, around which the median is computed.
dim	Image dimensions.

Definition at line 49 of file mrprior.c.

  {
//  oxxxo
//  xxxxx
//  xxXxx
//  xxxxx
//  oxxxo
  float w[21], *p;
 
  /* 1st row */
  p=inp-2*dim-1; w[0]=*p++; w[1]=*p++; w[2]=*p;
  /* 2nd row */
  p=inp-dim-2; w[3]=*p++; w[4]=*p++; w[5]=*p++; w[6]=*p++; w[7]=*p;
  /* 3rd row */
  p=inp-2; w[8]=*p++; w[9]=*p++; w[10]=*p++; w[11]=*p++; w[12]=*p;
  /* 4th row */
  p=inp+dim-2; w[13]=*p++; w[14]=*p++; w[15]=*p++; w[16]=*p++; w[17]=*p;
  /* 5th row */
  p=inp+2*dim-1; w[18]=*p++; w[19]=*p++; w[20]=*p;
  /* Median */
  return(fmedian(w, 21));
}

Referenced by do_prior(), and trmrp().

med9()

float med9	(	float *	inp,
		int	dim )

Compute 3x3 median from image data inside float array.

Returns

Returns the median value.

Parameters

inp	Pointer to central pixel in image data, around which the median is computed.
dim	Image dimensions.

Definition at line 15 of file mrprior.c.

  {
//  xxx
//  xXx
//  xxx
  float w[9], *p;
  int n=0;
 
  /* upper row */
  p=inp-dim-1; 
  w[n]=*p++; if(isfinite(w[n])) n++;
  w[n]=*p++; if(isfinite(w[n])) n++; 
  w[n]=*p; if(isfinite(w[n])) n++;
  /* mid row */
  p=inp-1; 
  w[n]=*p++; if(isfinite(w[n])) n++; 
  w[n]=*p++; if(isfinite(w[n])) n++; 
  w[n]=*p; if(isfinite(w[n])) n++;
  /* lower row */
  p=inp+dim-1; 
  w[n]=*p++; if(isfinite(w[n])) n++; 
  w[n]=*p++; if(isfinite(w[n])) n++; 
  w[n]=*p; if(isfinite(w[n])) n++;
  /* Median */
  return(fmedian(w, n));
}

Referenced by do_prior(), and trmrp().