imgs.cpp

一个google的OCR源码

      pixel |= *dest & ((1 << (8 - bit - bit)) - 1);
      *dest++ = pixel;           //new pixel
    }
  }
  else {
    pixperbyte = 8;
    dest += x / 8;               //offset on line
    bit = (inT8) (x % 8);        //offset in byte
    width += bit;
    pixel = *dest >> (8 - bit);
    while (width >= 8) {         //until all done
      for (; bit < 8; bit++) {
        pixel <<= 1;             //make space for new one
        pixel |= *src & 1;
        src += bytesperpix;
      }
      *dest++ = pixel;           //new pixel
      width -= 8;
      bit = 0;
    }
    width -= bit;
    if (width > 0) {             //until all done
      while (width > 0) {
        pixel <<= 1;             //make space for new one
        pixel |= *src & 1;
        src += bytesperpix;
        bit++;
        width--;
      }
      pixel <<= (8 - bit);       //shift rest
                                 //keep trainling bits
      pixel |= *dest & ((1 << (8 - bit)) - 1);
      *dest++ = pixel;           //new pixel
    }
  }
}


/**********************************************************************
 * put_column
 *
 * Put the supplied column buffer into the image.
 * The image is converted from 8bpp by simple assignment.
 **********************************************************************/

void IMAGE::put_column(                     //put image column
                       inT32 x,             //coord to start at
                       inT32 y,             //line to get
                       inT32 height,        //no of pixels to get
                       IMAGELINE *linebuf,  //line to copy to
                       inT32 margins        //margins in buffer
                      ) {
  uinT8 *src;                    //source pointer
  uinT8 *dest;                   //destination pointer
  inT8 bit;                      //bit index
  uinT8 pixel;                   //collected bits
  inT8 bytesperpix;              //in source

  this->check_legal_access (x, y, 1);
  this->check_legal_access (x, y + height - 1, 1);
  if (height > ysize - y)
    height = ysize - y;          //clip to image
  if (height <= 0)
    return;                      //nothing to do
                                 //source line
  src = linebuf->pixels + margins;
                                 //start of line
  dest = image + xdim * (ymax - 1 - y);

  if (linebuf->bpp == 24) {
    src++;
    bytesperpix = 3;
  }
  else
    bytesperpix = 1;

  if (bpp == 24 && linebuf->bpp == 24) {
    dest += x * bytesperpix;
    src--;
    for (; height > 0; --height) {
      *dest = *src++;
      *(dest + 1) = *src++;
      *(dest + 2) = *src++;
      dest -= xdim;
    }
  }
  else if (bpp == 24) {
    src--;
    dest += x * bytesperpix;
    for (; height > 0; --height) {
      pixel = *src++;
      *dest = pixel;
      *(dest + 1) = pixel;
      *(dest + 2) = pixel;
      dest -= xdim;
    }
  }
  else if (bpp > 4) {
    dest += x;                   //offset
    for (; height > 0; --height) {
      *dest = *src;
      src += bytesperpix;
      dest -= xdim;
    }
  }
  else if (bpp == 4) {
    dest += x / 2;               //offset on line
    if (x & 1) {
      for (; height > 0; --height) {
        *dest &= 0xf0;           //clean odd byte
        *dest |= *src & 0x0f;    //and copy it
        src += bytesperpix;
        dest -= xdim;
      }
    }
    else {
      for (; height > 0; --height) {
        *dest &= 0x0f;           //clean odd byte
        *dest |= *src << 4;
        src += bytesperpix;
        dest -= xdim;
      }
    }
  }
  else if (bpp == 2) {
    dest += x / 4;               //offset on line
    bit = (inT8) (x % 4);        //offset in byte
    bit = 6 - bit - bit;         //bit shift
    pixel = ~(3 << bit);         //mask
    for (; height > 0; --height) {
                                 //change 2 bits
      *dest = (*dest & pixel) | ((*src & 3) << bit);
      src += bytesperpix;
      dest -= xdim;
    }
  }
  else {
    dest += x / 8;               //offset on line
    bit = (inT8) (x % 8);        //offset in byte
    bit = 7 - bit;
    pixel = ~(1 << bit);
    for (; height > 0; --height) {
                                 //change 1 bit
      *dest = (*dest & pixel) | ((*src & 1) << bit);
      src += bytesperpix;
      dest -= xdim;
    }
  }
}


/**********************************************************************
 * check_legal_access
 *
 * Check that x,y are within the bounds of the image.
 * Call bufread if necessary to get the image into memory.
 **********************************************************************/

void IMAGE::check_legal_access(            //check coords are legal
                               inT32 x,    //coords to check
                               inT32 y,
                               inT32 xext  //xextent
                              ) {
  if (x < 0 || x >= xsize || y < 0 || y >= ysize || x + xext > xsize)
    BADIMAGECOORDS.error ("IMAGE::check_legal_access",
      ABORT, "(%d+%d,%d)", x, xext, y);
  if (y >= ymax)
    BADIMAGESEEK.error ("IMAGE::check_legal_access", ABORT, "(%d,%d)", x, y);
  if (y < ymin)
    bufread(y);  //read some more
}

#ifdef HAVE_LIBLEPT
// ONLY available if you have Leptonica installed.
/**********************************************************************
 * ToPix
 *
 * Make a Pix from this image.
 **********************************************************************/
Pix* IMAGE::ToPix() {
  int width = this->get_xsize();
  int height = this->get_ysize();
  int bpp = this->get_bpp();
  Pix* pix = pixCreate(width, height, bpp == 24 ? 32 : bpp);
  uint32* data = pixGetData(pix);
  IMAGELINE line;
  if (bpp == 24) {
    line.init(width * 3);
    line.set_bpp(24);
  } else {
    line.init(width);
  }
  switch (bpp) {
  case 1:
    for (int y = height - 1 ; y >= 0; --y) {
      this->get_line(0, y, width, &line, 0);
      for (int x = 0; x < width; ++x) {
        if (line.pixels[x])
          CLEAR_DATA_BIT(data, x);
        else
          SET_DATA_BIT(data, x);
      }
      data += pixGetWpl(pix);
    }
    break;

  case 8:
    // Greyscale just copies the bytes in the right order.
    for (int y = height - 1 ; y >= 0; --y) {
      this->get_line(0, y, width, &line, 0);
      for (int x = 0; x < width; ++x)
        SET_DATA_BYTE(data, x, line.pixels[x]);
      data += pixGetWpl(pix);
    }
    break;

  case 24:
    // Put the colors in the correct places in the line buffer.
    for (int y = height - 1 ; y >= 0; --y) {
      this->get_line(0, y, width, &line, 0);
      for (int x = 0; x < width; ++x, ++data) {
        SET_DATA_BYTE(data, COLOR_RED, line[x][RED_PIX]);
        SET_DATA_BYTE(data, COLOR_GREEN, line[x][GREEN_PIX]);
        SET_DATA_BYTE(data, COLOR_BLUE, line[x][BLUE_PIX]);
      }
    }
    break;

  default:
    tprintf("Cannot convert image to Pix with bpp = %d\n", bpp);
  }
  return pix;
}

/**********************************************************************
 * FromPix
 *
 * Copy from the given Pix into this image.
 **********************************************************************/
void IMAGE::FromPix(const Pix* src_pix) {
  // Leptonica doesn't const its inputs, but we don't change the input.
  Pix* pix = const_cast<Pix*>(src_pix);
  Pix* destroy_this_pix = NULL;

  int depth = pixGetDepth(pix);
  if (depth > 1 && depth < 8) {
    // Convert funny depths to 8 bit.
    destroy_this_pix = pixConvertTo8(pix, false);
    pix = destroy_this_pix;
    depth = pixGetDepth(pix);
  }
  int width = pixGetWidth(pix);
  int height = pixGetHeight(pix);
  const uint32* data = pixGetData(pix);
  this->create(width, height, depth == 32 ? 24 : depth);
  // For each line in the image, fill the IMAGELINE class and put it into the
  // destination image. Note that Tesseract stores images with the
  // bottom at y=0 and 0 is always black in grey and binary.
  IMAGELINE line;
  if (depth == 32) {
    line.init(width * 3);
    line.set_bpp(24);
  } else {
    line.init(width);
  }
  switch (depth) {
  case 1:
    // Binary images just flip the data bit.
    for (int y = height - 1 ; y >= 0; --y) {
      for (int x = 0; x < width; ++x)
        line.pixels[x] = GET_DATA_BIT(data, x) ^ 1;
      this->put_line(0, y, width, &line, 0);
      data += pixGetWpl(pix);
    }
    break;

  case 8:
    // Greyscale just copies the bytes in the right order.
    for (int y = height - 1 ; y >= 0; --y) {
      for (int x = 0; x < width; ++x)
        line.pixels[x] = GET_DATA_BYTE(data, x);
      this->put_line(0, y, width, &line, 0);
      data += pixGetWpl(pix);
    }
    break;

  case 32:
    // Put the colors in the correct places in the line buffer.
    for (int y = height - 1 ; y >= 0; --y) {
      for (int x = 0; x < width; ++x, ++data) {
        line[x][RED_PIX] = GET_DATA_BYTE(data, COLOR_RED);
        line[x][GREEN_PIX] = GET_DATA_BYTE(data, COLOR_GREEN);
        line[x][BLUE_PIX] = GET_DATA_BYTE(data, COLOR_BLUE);
      }
      this->put_line(0, y, width, &line, 0);
    }
    break;

  default:
    tprintf("Cannot convert Pix to image with bpp = %d\n", depth);
  }
  if (destroy_this_pix != NULL)
    pixDestroy(&destroy_this_pix);
}
#endif  // HAVE_LIBLEPT

/*************************************************************************
 * convolver()
 *
 * Calls the specified function for each pixel in the image, passing in an m x n
 * window of the image, centred on the pixel.  The convolution function returns
 * a new value for the pixel, based on the window.
 *
 * At the edges of the image, the window is padded to white pixels.
 *************************************************************************/

void
IMAGE::convolver (               //Map fn over window
inT32 win_width,                 //Window width
inT32 win_height,                //Window height
void (*convolve) (               //Conv Function
uinT8 ** pixels,                 //Of window
uinT8 bytespp,                   //1 or 3 for colour
inT32 win_wd,                    //Window width
inT32 win_ht,                    //Window height
uinT8 ret_white_value,           //White value to RETURN
uinT8 * result)                  //Ptr to result pix
) {
  IMAGELINE new_row;             //Replacement pixels
  IMAGELINE *old_rows;           //Rows being processed
  inT32 oldest_imline;           //Next imline to replace
  uinT8 **window;                //ptrs to pixel rows
  uinT8 **winmax;                //ptrs to pixel rows
  uinT8 **win;                   //ptrs to pixel rows
  inT32 current_row;             //Row being calculated
  inT32 current_col;             //Col being calculated
  inT32 row = 0;                 //Next row to get

  inT32 i, j;
  uinT8 *pix;
  uinT8 *max;
  inT32 xmargin = win_width / 2;
  inT32 ymargin = win_height / 2;
  uinT8 white = get_white_level ();
  const uinT8 max_white = 255;
  float white_scale = (float) 255 / get_white_level ();

  if (((win_width % 2) == 0) ||
    ((win_height % 2) == 0) ||
    (win_height < 3) ||
    (win_width < 3) || (win_height > ysize / 2) || (win_width > xsize / 2))
    BADWINDOW.error ("IMAGE::convolver",
      ABORT, "(%d x %d)", win_width, win_height);

  new_row.init (xsize * bytespp);
  new_row.set_bpp (bpp);
  old_rows = new IMAGELINE[win_height];
  for (i = 0; i < win_height; i++) {
    old_rows[i].init ((xsize + 2 * xmargin) * bytespp);
    old_rows[i].set_bpp (bpp);
  }

  window = (uinT8 **) alloc_mem (win_height * sizeof (uinT8 *));
  winmax = window + win_height;

  /* Make bottom border */
  for (oldest_imline = 0; oldest_imline < ymargin; oldest_imline++) {
    pix = old_rows[oldest_imline].pixels;
    max = pix + (xsize + 2 * xmargin) * bytespp;
    while (pix < max)
      *pix++ = max_white;
  }
  /* Initialise remaining rows but one*/
  for (; oldest_imline < win_height - 1; oldest_imline++) {
    get_line (0, row++, xsize, &old_rows[oldest_imline], xmargin);
    if (max_white != white) {
      pix = old_rows[oldest_imline].pixels;
      max = pix + (xsize + 2 * xmargin) * bytespp;
      while (pix < max) {
        *pix = (uinT8) (*pix * white_scale);
        ++pix;
      }
    }
  }

  /* Image Processing */

  for (current_row = 0; current_row < ysize;) {
    /* Get next row and re-initialise window array */
    if (row < ysize) {
      get_line (0, row++, xsize, &old_rows[oldest_imline], xmargin);
      if (max_white != white) {
        pix = old_rows[oldest_imline].pixels;
        max = pix + (xsize + 2 * xmargin) * bytespp;
        while (pix < max) {
          *pix = (uinT8) (*pix * white_scale);
          ++pix;
        }
      }
    }
    else {
      pix = old_rows[oldest_imline].pixels;
      max = pix + (xsize + 2 * xmargin) * bytespp;
      while (pix < max)
        *pix++ = max_white;
    }
    oldest_imline++;
    if (oldest_imline >= win_height)
      oldest_imline = 0;

    /* Process line */
    pix = new_row.pixels;
    for (current_col = 0; current_col < xsize;) {
      /* Set up window ptrs */
      if (current_col == 0) {
        j = oldest_imline;
        for (i = 0; i < win_height; i++) {
          window[i] = old_rows[j++].pixels;
          if (j >= win_height)
            j = 0;
        }
      }
      else {
        for (win = window; win < winmax; (*win++) += bytespp);
        //Move along rows
      }

      convolve(window, bytespp, win_width, win_height, white, pix);
      pix += bytespp;
      current_col++;
    }

    put_line (0, current_row, xsize, &new_row, 0);
    new_row.init ();
    new_row.set_bpp (bpp);
    current_row++;
  }
}