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/****************************************************************************/
/* */
/* IMG* Image Processing Tools Library */
/* Program: imgZeros.c */
/* Author: Simon A.J. Winder */
/* Date: Thu Oct 20 20:46:02 1994 */
/* Copyright (C) 1994 Simon A.J. Winder */
/* */
/****************************************************************************/
#include "tools.h"
#define PRGNAME "Zeros"
#define ERROR(e) imgError(e,PRGNAME)
int main(int argc,char **argv)
{
it_image *in1,*out1;
int width,height,x,y;
int v_x,v_y,x_end,y_end,bit;
double aa,bb,cc,dd,ee;
IFHELP
{
fprintf(stderr,"img%s - Zero-crossing detector\n",PRGNAME);
fprintf(stderr,"img%s [noborder] \n",PRGNAME);
fprintf(stderr," stdin: Float\n");
fprintf(stderr," stdout: pbm\n");
fprintf(stderr," If the argument is present there will be no border\n");
exit(0);
}
imgStart(PRGNAME);
do {
in1=i_read_image_file(stdin,IT_FLOAT,IM_FRAGMENT);
if(in1==NULL)
ERROR("can't import image file");
width=in1->width;
height=in1->height;
out1=i_create_image(width,height,IT_BIT,IM_FRAGMENT);
if(out1==NULL)
ERROR("out of memory");
/* Look for places where there is a zero-crossing */
v_y=in1->valid_y+1;
v_x=in1->valid_x+1;
y_end=v_y+in1->valid_height-2;
x_end=v_x+in1->valid_width-2;
for(y=v_y;y<y_end;y++)
for(x=v_x;x<x_end;x++)
{
bit=0;
aa=im_float_value(in1,x,y-1);
bb=im_float_value(in1,x-1,y);
cc=im_float_value(in1,x,y);
dd=im_float_value(in1,x+1,y);
ee=im_float_value(in1,x,y+1);
/* Do a test to see if + centre, - elsewhere */
if(cc>0.0 && (aa<0.0 || bb<0.0 || dd<0.0 || ee<0.0))
bit=1;
if(cc==0.0)
{
/* Do a + shaped test for -0+ or +0- sequences */
if(aa>0.0 && ee<0.0 || aa<0.0 && ee>0.0 ||
bb>0.0 && dd<0.0 || bb<0.0 && dd>0.0)
bit=1;
else
{
/* Do a diagonal test */
aa=im_float_value(in1,x-1,y+1);
bb=im_float_value(in1,x+1,y+1);
dd=im_float_value(in1,x-1,y-1);
ee=im_float_value(in1,x+1,y-1);
if(aa>0.0 && ee<0.0 || aa<0.0 && ee>0.0 ||
bb>0.0 && dd<0.0 || bb<0.0 && dd>0.0)
bit=1;
}
}
im_put_bit_value(out1,x,y,bit);
}
/* Not actually needed cos you can't send this info with a bit image */
out1->valid_x=v_x;
out1->valid_y=v_y;
out1->valid_width=in1->valid_width-2;
out1->valid_height=in1->valid_height-2;
i_destroy_image(in1);
if(argc==1)
{
/* Draw a box */
v_x--;
v_y--;
for(x=v_x;x<=x_end;x++)
{
im_put_bit_value(out1,x,v_y,1);
im_put_bit_value(out1,x,y_end,1);
}
for(y=v_y;y<=y_end;y++)
{
im_put_bit_value(out1,v_x,y,1);
im_put_bit_value(out1,x_end,y,1);
}
}
i_write_image_file(stdout,out1,IF_BINARY);
i_destroy_image(out1);
} while(!feof(stdin));
imgFinish(PRGNAME);
return(0);
}
/* Version 1.0 (Oct 1994) */
/* Version 1.1 (Nov 1994) */
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