filter.c

本文档包括了几何矫正的主体内容

/*
 *  <filter.c>
 *  this file include all functions in relation to filter 
 */
#include <filter.h>

double sin_c(double x);
/*
 *  cubicFunctionTable
 *
 *  compute cubic filter template
 */ 
void
cubicFunctionTable(cubicWidth,cubicHeight,tabNum,cubicTable)
	long cubicWidth,cubicHeight;  /* width and height filter template */
	long tabNum;                  /* discret dot num */
	double *cubicTable;           /* filter template */
{
	long cw,ch,tx,ty;   /* index varaible */
	double ival;     /* interval for template */
	double startx,starty;
	double tmpx,tmpy;
	
#if 0
        long point_num = 0;
	printf("filter width = %d height = %d tabnum = %d\n",
			cubicWidth,cubicHeight,tabNum);
#endif
	if(!cubicTable) {
		printf("Error: Memory Allocation for Filter Template\n");
		exit(1);
	}
#if 0
	for(tn=0;tn<tabNum * tabNum;tn++) {
	     for( ch = 0;ch < cubicHeight;ch++ ) {
	        	for ( cw = 0;cw < cubicWidth;cw++ ) {
		        	*cubicTable = tn*cubicWidth*cubicHeight + ch*cubicWidth + cw;
			        cubicTable++;
		        }
	     }
	}
#endif		
	ival = 1./tabNum;
	startx =-1. +  cubicWidth/2.;
	starty =-1. +  cubicHeight/2.;
	for( ty = 0; ty <tabNum; ty++ ) {	
	  for( tx =0;tx <tabNum;tx++ ) {
	     tmpx = startx;
	     tmpy = starty;
	     for( ch = 0; ch<cubicHeight;ch++ ) {
	       for( cw=0;cw<cubicWidth;cw++ ) {
		       *cubicTable = sin_c(tmpx)*sin_c(tmpy);
		       /*printf("%f %f %f,%f\n",tmpx,tmpy,sin_c(tmpx),sin_c(tmpy));*/
		       cubicTable++;
		       tmpx -= 1.;
	       }
	       tmpy -= 1.;
	       tmpx = startx;
	     }
             startx += ival;
	  } /* for(tx.. */
	  startx = -1. + cubicWidth/2.;
	  starty += ival;
	} /* for(ty.. */
			
}

/*
 *  sin_c(x)
 * 
 *                    | 1-2x^2+|x|^3       |x| < 1
 *  sin_c(x) =? s(x) = | 4-8|x|+5x^2-|x|^3  1<= |x| <2
 *                    | 0                  |x|>= 2
 */  
double 
sin_c(x)
	double x;
{
	if (x < 0) x = -x;
	if (x < 1) {
		return x*x*(x-2.)+1. ;
	} else if (x >=2) {
		return 0. ;
	} else {
		return  x*(x*(-x+5)-8)+4.;
	}
}