read_pgm(image,filename,width,height,depth)char filename[];unsigned char image[MAX_SIZE][MAX_SIZE];int *width,*height,*depth;{    FILE *fp_in;    int x,y;    char ch,str[1000];    if ((fp_in=fopen(filename,"r")) == NULL) {        fprintf(stderr,"cant open %s\n",filename);        exit(-2);    }    /* skip image type and comments in header */    fgets(str,255,fp_in);    do        fgets(str,255,fp_in);    while (str[0] == '#');    /* read image parameters */    /* the first line has already been read */    sscanf(str,"%d %d",width,height);    fscanf(fp_in,"%d",depth);    /* skip CR */    getc(fp_in);    if ((*width > MAX_SIZE) || (*height > MAX_SIZE)) {        fprintf(stderr,"ERROR: Maximum image size is %d x %d\n",            MAX_SIZE,MAX_SIZE);        exit(-1);    }    if (*depth != 255) {        fprintf(stderr,"ERROR: depth = %d; (instead of 255)\n",*depth);        exit(-1);    }    /***    printf("image size: %d x %d\n",*width,*height);    printf("reading image from %s\n",filename);    ***/    for (y = 0; y < *height; y++)       for (x = 0; x < *width; x++)            image[x][y] = getc(fp_in);    /* check the image file was the correct size */    if (feof(fp_in)) {        /***        fprintf(stderr,"ERROR: premature end of file\n");        exit(-1);        ***/    }    else        if (getc(fp_in) != EOF) {            fprintf(stderr,"ERROR: extra characters in file\n");            exit(-1);        }    fclose(fp_in);}write_pgm(image,filename,width,height)unsigned char image[MAX_SIZE][MAX_SIZE];char *filename;int width,height;{    FILE *fp_out;    int x,y;    if ((fp_out = fopen(filename,"w")) == NULL) {        fprintf(stderr,"cant open %s\n",filename);        exit(-1);    }    fprintf(fp_out,"P5\n");    fprintf(fp_out,"#created by Paul Rosin\n");    fprintf(fp_out,"%d %d\n",width,height);    fprintf(fp_out,"255\n");    /***    printf("writing image to %s\n",filename);    ***/    for (y = 0; y < height; y++)        for (x = 0; x < width; x++)            putc(image[x][y],fp_out);    fclose(fp_out);}