/* * chamfer 3-4 distance transform * * CVGIP v34, pp344, 1986 * * Paul Rosin 1/91 * extended & improved 2/93 * simplified serial version 7/94 */#include <stdio.h>#ifndef FALSE# define FALSE 0# define TRUE (!FALSE)#endif#define MIN(a,b)     (((a) < (b)) ? (a) : (b))#define MAX_SIZE 3000#include "pgmio.h"unsigned char image[MAX_SIZE][MAX_SIZE];int image2[MAX_SIZE][MAX_SIZE];int height,width,depth;main(argc,argv)int argc;char *argv[];{    int i,j,x,y;    int v[9];    int min_val;    char *infile,*outfile;    infile = outfile = NULL;    /* parse command line */    for (i = 1; i < argc; i++) {        if (argv[i][0] == '-') {            switch(argv[i][1]) {                case 'i':                    i++;                    infile = argv[i];                    break;                case 'o':                    i++;                    outfile = argv[i];                    break;                default:                    printf("unknown option %s\n",argv[i]);                    options(argv[0]);            }        }        else {            printf("unknown option %s\n",argv[i]);            options(argv[0]);        }    }    if ((infile == NULL || outfile == NULL))        options(argv[0]);    read_pgm(image,infile,&width,&height,&depth);    /* copy to integer image */    for (y = 0; y < height; y++)        for (x = 0; x < width; x++)            image2[x][y] = (unsigned char)image[x][y];    /* forward pass */    for (y = 1; y < height-1; y++) {        for (x = 1; x < width-1; x++) {            v[0] = image2[x-1][y-1] + 4;            v[1] = image2[x  ][y-1] + 3;            v[2] = image2[x+1][y-1] + 4;            v[3] = image2[x-1][y  ] + 3;            v[4] = image2[x  ][y  ];            min_val = v[0];            for (i = 1; i < 5; i++)                if (v[i] < min_val)                    min_val = v[i];            image2[x][y] = min_val;        }    }    /* backward pass */    for (y = height-2; y >= 1; y--) {        for (x = width-2; x >= 1; x--) {            v[0] = image2[x-1][y+1] + 4;            v[1] = image2[x  ][y+1] + 3;            v[2] = image2[x+1][y+1] + 4;            v[3] = image2[x+1][y  ] + 3;            v[4] = image2[x  ][y  ];            min_val = v[0];            for (i = 1; i < 5; i++)                if (v[i] < min_val)                    min_val = v[i];            image2[x][y] = min_val;        }    }    /* set corners high for the time being */    image2[0][0] = image2[0][height-1] = image2[width-1][0] = image2[width-1][height-1] = 255;    /* do left edges too */    x = 0;    for (y = 1; y < height-1; y++) {        v[0] = image2[x+1][y-1] + 4;        v[1] = image2[x+1][y  ] + 3;        v[2] = image2[x+1][y-1] + 4;        min_val = 255;        for (i = 0; i < 3; i++)            if (v[i] < min_val)                min_val = v[i];        image2[x][y] = min_val;    }    /* do right edges too */    x = width-1;    for (y = 1; y < height-1; y++) {        v[0] = image2[x-1][y-1] + 4;        v[1] = image2[x-1][y  ] + 3;        v[2] = image2[x-1][y-1] + 4;        min_val = 255;        for (i = 0; i < 3; i++)            if (v[i] < min_val)                min_val = v[i];        image2[x][y] = min_val;    }    /* do top edges too */    y = 0;    for (x = 1; x < width-1; x++) {        v[0] = image2[x-1][y+1] + 4;        v[1] = image2[x  ][y+1] + 3;        v[2] = image2[x+1][y+1] + 4;        min_val = 255;        for (i = 0; i < 3; i++)            if (v[i] < min_val)                min_val = v[i];        image2[x][y] = min_val;    }    /* do bottom edges too */    y = height-1;    for (x = 1; x < width-1; x++) {        v[0] = image2[x-1][y-1] + 4;        v[1] = image2[x  ][y-1] + 3;        v[2] = image2[x+1][y-1] + 4;        min_val = 255;        for (i = 0; i < 3; i++)            if (v[i] < min_val)                min_val = v[i];        image2[x][y] = min_val;    }    /* clamp at 255 since output is 8 bit */    for (y = 0; y < height; y++)        for (x = 0; x < width; x++)            image2[x][y] = MIN(255,image2[x][y]);    /* copy back to unsigned char image */    for (y = 0; y < height; y++)        for (x = 0; x < width; x++)            image[x][y] = (unsigned char)image2[x][y];    write_pgm(image,outfile,width,height);}options(progname)char *progname;{    printf("usage: %s [options]\n",progname);    printf("     -i infile  binary edge map\n");    printf("     -o outfile output distance map\n");    exit(-1);}