pdf417_dec.c

PDF417编码的算法的源程序

  int pixel_new;
  int debug;


  debug = 0;

  for(jj = 0; jj < pixel_cnt; jj += 1)
    {
      if ( line_data[jj] > line_threshold )
        {
          line_data[jj] = 127;
        }
      else
	{
	  line_data[jj] = 0;
        }
    }

  
  if ( debug) 
    {
      printf("End smooth line \n");
    }
}

/**************************************************************************
 *  line_fast                                                             *
 *    gets a line using Bresenham's line-drawing algorithm, which uses   *
 *    no multiplication or division.                                      *
 *    gets data from pixel array and puts in line_data                    *
 **************************************************************************/

void line_fast(int x1, int y1, int x2, int y2)
{
  int i,dx,dy,sdx,sdy,dxabs,dyabs,x,y,px,py;

  dx=x2-x1;      /* the horizontal distance of the line */
  dy=y2-y1;      /* the vertical distance of the line */
  dxabs=abs(dx);
  dyabs=abs(dy);
  sdx=sgn(dx);
  sdy=sgn(dy);
  x=dyabs>>1;
  y=dxabs>>1;
  px=x1;
  py=y1;

  pixel_cnt = 0;

  get_pixel(px,py);

  if (dxabs>=dyabs) /* the line is more horizontal than vertical */
  {
    for(i=0;i<dxabs;i++)
    {
      y+=dyabs;
      if (y>=dxabs)
      {
        y-=dxabs;
        py+=sdy;
      }
      px+=sdx;
      get_pixel(px,py);
    }
  }
  else /* the line is more vertical than horizontal */
  {
    for(i=0;i<dyabs;i++)
    {
      x+=dxabs;
      if (x>=dyabs)
      {
        x-=dyabs;
        px+=sdx;
      }
      py+=sdy;
      get_pixel(px,py);
    }
  }
}

/**************************************************************************
 *  line_fast_post                                                       *
 *    gets a line using Bresenham's line-drawing algorithm, which uses   *
 *    no multiplication or division.                                      *
 *   get data from the pix_out and puts it in post_line_data              *
 **************************************************************************/

void line_fast_post(int x1, int y1, int x2, int y2)
{
  int i,dx,dy,sdx,sdy,dxabs,dyabs,x,y,px,py;

  dx=x2-x1;      /* the horizontal distance of the line */
  dy=y2-y1;      /* the vertical distance of the line */
  dxabs=abs(dx);
  dyabs=abs(dy);
  sdx=sgn(dx);
  sdy=sgn(dy);
  x=dyabs>>1;
  y=dxabs>>1;
  px=x1;
  py=y1;

  post_pixel_cnt = 0;

  get_pixel_post(px,py);

  if (dxabs>=dyabs) /* the line is more horizontal than vertical */
  {
    for(i=0;i<dxabs;i++)
    {
      y+=dyabs;
      if (y>=dxabs)
      {
        y-=dxabs;
        py+=sdy;
      }
      px+=sdx;
      get_pixel_post(px,py);
    }
  }
  else /* the line is more vertical than horizontal */
  {
    for(i=0;i<dyabs;i++)
    {
      x+=dxabs;
      if (x>=dyabs)
      {
        x-=dyabs;
        px+=sdx;
      }
      py+=sdy;
      get_pixel_post(px,py);
    }
  }
}

/**************************************************************************
 *  line_fast norm                                                      *
 *    gets a line using Bresenham's line-drawing algorithm, which uses   *
 *    no multiplication or division.                                      *
 *    gets data from pixel_array but puts result in norm_line_data        *
 **************************************************************************/

void line_fast_norm(int x1, int y1, int x2, int y2)
{
  int i,dx,dy,sdx,sdy,dxabs,dyabs,x,y,px,py;

  dx=x2-x1;      /* the horizontal distance of the line */
  dy=y2-y1;      /* the vertical distance of the line */
  dxabs=abs(dx);
  dyabs=abs(dy);
  sdx=sgn(dx);
  sdy=sgn(dy);
  x=dyabs>>1;
  y=dxabs>>1;
  px=x1;
  py=y1;

  pixel_cnt = 0;

  get_pixel_norm(px,py);

  if (dxabs>=dyabs) /* the line is more horizontal than vertical */
  {
    for(i=0;i<dxabs;i++)
    {
      y+=dyabs;
      if (y>=dxabs)
      {
        y-=dxabs;
        py+=sdy;
      }
      px+=sdx;
      get_pixel_norm(px,py);
    }
  }
  else /* the line is more vertical than horizontal */
  {
    for(i=0;i<dyabs;i++)
    {
      x+=dxabs;
      if (x>=dyabs)
      {
        x-=dyabs;
        px+=sdx;
      }
      py+=sdy;
      get_pixel_norm(px,py);
    }
  }
}

// draw a normal at a point

void draw_normal(int nx, int ny, int nslope, int ndir, int ylen)
{
  int ii;
  int xinc, yinc;
  int dark_percent;

  int bits_on_cnt;
  int num_dark;
  int first_dark;
  int first_dark_ind;
  int debug;

  debug = 0;

  if (debug)
    {
     printf("In draw normal , x,y = %d %d \n",nx, ny );
     printf("Slope = %d \n", nslope);
     printf("ylen = %d \n", ylen);
     printf("dir = %d \n",ndir);
    }


  if ( ndir == 1)  // positive x and positive y incr
    {
       yinc = (ylen);
       xinc = (((ylen) * slope) / 100);
      
      line_fast_norm(nx, ny, nx + xinc, ny+yinc);
    }

  if ( ndir == -1)   // negative x incr and positive y incr
    {
       yinc = (ylen);
       xinc = 0- (( (ylen) * slope) / 100);

      line_fast_norm(nx, ny, nx + xinc, ny+yinc);
    }

  num_dark = 0;

  first_dark = FALSE;
  first_dark_ind = -1;

  for ( ii = 0; ii < pixel_cnt; ii += 1)
    {
      if ( norm_line_data[ii] > dark_threshold)
	{
          if ( first_dark == FALSE)
	    {
	      first_dark = TRUE;
              first_dark_ind = ii;
            }
         
	  num_dark += 1;
        }
      if (debug) {  printf("norm line %d = %d \n",ii, norm_line_data[ii]); }

    }

  if (debug)
    {
      printf("num_dark = %d \n",num_dark);
      printf("First dark at = %d \n",first_dark_ind);
    }

  dark_percent = (num_dark * 100) / pixel_cnt;

  if (debug) { printf("Dark percent = %d \n", dark_percent); }

  norm_fdark_ind = first_dark_ind;
  
}


 // use a binary search to find the index in the
 // bit_array of the pdf barcode
 //
 int find_index( long inbits, int code_in, int column, int row)
 {

   int ii;
   int found_index;
   int bit_index;
   int bit_increment;
   int found;
   int less_than_flag;

   int debug;

   bit_index = 1392;

   bit_increment = 696;

   found = FALSE;

   less_than_flag = FALSE;

   debug = 0;

   if ( debug) { printf("Inbits = %x \n", inbits); }

   while (( found == FALSE ) && (bit_increment > 11 ))
     {
       if (debug)
	 {
	     printf(" bit_array val = %x , inbits = %x \n",
				  bit_array[bit_index], inbits); 
	 }
      if (bit_array[bit_index] > inbits)
	{
	 bit_index = bit_index - bit_increment;
	 less_than_flag = FALSE;
	}
      else
	{
	  if (bit_array[bit_index] == inbits)
	    {
	      found = TRUE;
	      found_index = bit_index;
	    }
	  else  // less than 
	    {
	     bit_index = bit_index + bit_increment;
	     less_than_flag = TRUE;
	    }
	}

      bit_increment = bit_increment / 2;

      if (debug)
	{
	 printf("In find loop , bit_increment = %d \n", bit_increment);
	 printf("In find loop , bit_index = %d \n", bit_index);
	}

     }

  if ( found == FALSE)
    {
      ii = 0;
      if ( debug) { printf("no less than flag , bit_index = %d \n",bit_index); }
      while (( found == FALSE) && ( ii < 25) && ( bit_index < 2759))
	{
	   if (bit_array[bit_index + ii] == inbits)
	     {
	      found = TRUE;
	      found_index = bit_index + ii;
	     }
	   ii += 1;        
	}
    }

  if ( found == FALSE)
    {
      ii = 0;
      if (debug) { printf("less than flag , bit_index = %d \n",bit_index); }
      while (( found == FALSE) && ( ii > -25) && ( bit_index > 26))
	{
	  if ( bit_index + ii > 0)
	   {
	    if (bit_array[bit_index + ii] == inbits)
	     {
	      found = TRUE;
	      found_index = bit_index + ii;
	     }
	   }
	   ii -= 1;        
	}
    }

  if (found == FALSE)
    {

      // do an exhaustive search

     ii = 0;

     if (debug) { printf("Doing exhaustive search \n"); }

     while ( ( ii < 2784 ) && (found == FALSE))
       {
	  if ( bit_array[ii] == inbits)
	    {
	     found = TRUE;
	     found_index = ii;
	    }
	   ii += 1;
       }
    }

    if (found == FALSE)
      {
	if (code_in == 0)
	  {
           printf(" Top left module not found in bit_array = 0x%x \n", inbits);
          }

	if (code_in == 1)
	  {
           printf(" Bottom left module not found in bit_array = 0x%x \n", inbits);
          }
	if (code_in == 2)
	  {
	    if ( debug) 
              {
               printf(" Column,row module not found in bit_array = 0x%x \n", inbits);
               printf(" Column = %d row = %d\n", column, row);
              }
          }
       return(-1);
      }
    else
      {
       return( found_index );
      }

 }


// find the differences in the x ( row ) grey values 
//  for each y location in pix_col data
//

void do_pixcol_diffy(int inwidth, int inheight)
{
  int ii;
  int jj;
  int kk;
  int diff_data[OUT_MAX_X_PIXEL];
  int diff_tots[OUT_MAX_X_PIXEL];
  int first_deriv[OUT_MAX_X_PIXEL];
  int diff_tots_sorted[OUT_MAX_X_PIXEL];
  int total_diff;
  int prev_total;
  long cum_total;
  long avg_total;
  int prev_line;
  int x_space;
  int est_bar_width;
  int debug;


  debug = 0;

  diff_data[0] = 0;
  diff_data[1] = 0;
  diff_data[2] = 0;

  cum_total = 0;
  total_diff = 0;
  prev_total = 0;
  if (debug)
    {
       printf(" In do pix_col_diffy, inwidth, inheight = %d %d \n",
                           inwidth, inheight);
    }
  for ( jj = 3; jj < inwidth; jj += 1)
    {
      total_diff = 0;
      for ( ii = 0; ii < inheight ; ii += 1)
	{
      diff_data[ii] = abs(pix_cols[jj][ii].greyval - pix_cols[jj-3][ii].greyval);
      total_diff = total_diff + diff_data[ii];
        }
      diff_tots[jj]= total_diff;
      cum_total = total_diff + cum_total;
      first_deriv[jj] = total_diff - prev_total;
      prev_total = total_diff;
     }  

  if ( inwidth != 0)
    {
     avg_total = cum_total/inwidth;
    }
  else
    {
      printf("In pixcol_diff_y, inwidth = 0 , internal error \n");
      exit(0);
    }


  if (debug)
    { printf("avg total = %d \n", avg_total); }

  for ( jj = 0; jj < inwidth; jj += 1)
    {
      if (debug)
        {
      printf(" jj = %d diff_tots = %d 1st deriv = %d \n",jj, diff_tots[jj],
                first_deriv[jj]);
        }
    }

  kk = 0;
  prev_line = 0;
  for ( jj = 5; jj < inwidth; jj += 1)
    {
      if (( first_deriv[jj] > 0) && ( first_deriv[jj+1] < 0))
        {
          if ( (long) diff_tots[jj] > (avg_total/2 ))
            {
             
              if ( kk < MAX_LINES_X)
		{
		  if ( kk > 0)
                    {
                     if (( jj - pix_col_xline[kk-1]) > (int) (best_onewf /2))
		      {
		       pix_col_xline[kk] = jj;
                       x_space = jj - prev_line;
                       prev_line = jj;  
                       kk += 1;
		      }
                    }
                  else
                    {
                    if ( jj  > (int) (best_onewf /2))
		      {
		       pix_col_xline[kk] = jj;
                       x_space = jj - prev_line;
                       prev_line = jj;  
                       kk += 1;
		      }
                    }
                }
              else
		{
		  printf("Too many vertical lines in pix_col \n");
                }
              if (debug)
                {
                 printf("Candidate at jj = %d  x_space = %d \n",jj, x_space);
                }
            }
        }
    }
    
  vert_line_cnt = kk;

  if ( kk != 0)
    {
     est_bar_width = (inwidth * 10 )/ kk;