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/****************************************************************************/
/* */
/* IMG* Image Processing Tools Library */
/* Program: imgEdgeSynth.c */
/* Author: Simon A.J. Winder */
/* Date: Thu Oct 20 20:45:37 1994 */
/* Copyright (C) 1994 Simon A.J. Winder */
/* */
/****************************************************************************/
#include "tools.h"
#define STACKSIZE 1000
#define PRGNAME "EdgeSynth"
#define ERROR(e) imgError(e,PRGNAME)
#define push(p,q) {stack[sp].x=(p);stack[sp++].y=(q);}
#define pull() ((sp>0)?(&(stack[--sp])):NULL)
#define stack_full (sp>=STACKSIZE)
/* Stack of x,y coordinates */
static it_point stack[STACKSIZE];
static int sp;
int main(int argc,char **argv)
{
it_image *i1,*i2,*i3;
int width,height,x,y,xx,yy,i,j;
double low_thresh,high_thresh;
it_float *flt_ptr;
it_point *p;
IFHELP
{
fprintf(stderr,"img%s - Canny two level edge synth operator\n",
PRGNAME);
fprintf(stderr,"img%s [low_thresh high_thresh]\n",
PRGNAME);
fprintf(stderr," stdin: Float\n");
fprintf(stderr," stdout: pbm\n");
exit(0);
}
imgStart(PRGNAME);
low_thresh=high_thresh=0.0;
if(argc>4)
ERROR("invalid arguments");
if(argc>1)
low_thresh=atof(argv[1]);
if(argc>2)
high_thresh=atof(argv[2]);
do {
/* Load the edge image */
i2=i_read_image_file(stdin,IT_FLOAT,IM_CONTIG);
if(i2==NULL)
ERROR("can't import image file");
width=i2->width;
height=i2->height;
if(argc==1)
{
low_thresh=i2->max_value*0.1;
high_thresh=i2->max_value*0.35;
}
i1=i_create_image(width,height,IT_BIT,IM_CONTIG);
if(i1==NULL)
ERROR("out of memory");
/* Make image to hold high threshold map */
i3=i_create_image(width,height,IT_BIT,IM_CONTIG);
if(i3==NULL)
ERROR("out of memory");
/* Make low and high thresholded bit images */
for(y=0;y<height;y++)
{
flt_ptr=im_float_row(i2,y);
for(x=0;x<width;x++,flt_ptr++)
{
if(*flt_ptr>low_thresh)
im_put_bit_value(i1,x,y,1);
if(*flt_ptr>=high_thresh)
im_put_bit_value(i3,x,y,1);
}
}
i_destroy_image(i2);
/* Create output bit image */
i2=i_create_image(width,height,IT_BIT,IM_CONTIG);
if(i2==NULL)
ERROR("out of memory");
/* Go through image writing out all lower threshold lines */
/* that are present to some extent in the high threshold image */
for(y=0;y<height;y++)
for(x=0;x<width;x++)
{
/* Use high threshold image for a seed */
if(im_get_bit_value(i3,x,y))
{
/* Stack starting point and clear from low thresh image */
push(x,y);
im_put_bit_value(i1,x,y,0);
/* Trace the line from x,y */
while((p=pull())!=NULL)
{
/* Write the point to the output image and delete */
/* from the high threshold image */
xx=p->x;
yy=p->y;
im_put_bit_value(i2,xx,yy,1);
im_put_bit_value(i3,xx,yy,0);
/* Stack and delete points we want to go to next */
for(i=yy-1;i<yy+2;i++)
for(j=xx-1;j<xx+2;j++)
if(i>0 && i<height && j>0 && j<width)
if(im_get_bit_value(i1,j,i))
{
if(stack_full)
ERROR("pixel stack overflowed");
push(j,i);
im_put_bit_value(i1,j,i,0);
}
}
}
}
i_destroy_image(i1);
i_destroy_image(i3);
i_write_image_file(stdout,i2,IF_BINARY);
i_destroy_image(i2);
} while(!feof(stdin));
imgFinish(PRGNAME);
return(0);
}
/* Version 1.0 (Oct 1994) */
/* Version 1.1 (Nov 1994) */
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