fmaskrot.c

image processing including fourier,wavelet,segmentation etc.

/*--------------------------- Commande MegaWave -----------------------------*/
/* mwcommand
   name = {fmaskrot};
   version = {"1.0"};
   author = {"Lionel Moisan"};
   function = {"crop the central circular region of a Fimage"};
   usage = {  
'b':[bg=0.0]->bg   "background grey value, default: 0.0",
's':[s=10.]->s     "linear transition support (in pixels), default 10.0",
in->in             "input Fimage",
out<-out           "output Fimage"

};
*/

#include <stdio.h>
#include <math.h>
#include "mw.h"

/* NB : calling this module with out=in is possible */

Fimage fmaskrot(in,out,bg,s)
     Fimage in,out;
     float *bg,*s;
{
  int nx,ny,x,y,adr;
  double cx,cy,r,d;

  nx = in->ncol;
  ny = in->nrow;

  out = mw_change_fimage(out,ny,nx);

  cx = 0.5*(double)(nx-1);
  cy = 0.5*(double)(ny-1);
  r = (cx<cy?cx:cy);

  for (x=nx;x--;) for (y=ny;y--;) {
    adr = y*nx+x;
    d = hypot((double)x-cx,(double)y-cy);
    if (d>=r) out->gray[adr] = *bg;
    else if (d<=r-*s) out->gray[adr] = in->gray[adr];
    else out->gray[adr] = (*bg*(*s-(float)(r-d)) + 
			   in->gray[adr]*(float)(r-d)) /(*s);
  }
  return(out);
}