Pointer to Decompressed Image

Hello!

I am trying to decompress a .TIF file, then get a pointer to the decompressed image buffer.  How can I do this?  It seems like it should be obvious, because isn't that the point of the decompression functions?  My code is essentially copying the code from the example:
L_INT StartDecompressBufferFirstExample(L_VOID)
{
   L_INT nRet;
   L_TCHAR *szFileName = TEXT("C:\\Program Files\\LEAD Technologies\\LEADTOOLS 15\\Images\\packbits.tif");
   L_HANDLE fd;
   L_UCHAR *pBuf = NULL;
   BITMAPHANDLE Bitmap;
   FILEINFO TempFileInfo;
   L_INT  nRowsPerStrip=0;
   STARTDECOMPRESSDATA StartDecompressData;
   DECOMPRESSDATA      DecompressData;
   L_INT  nIndex = 0;
   HGLOBAL hDecompress;
   L_INT StripOffsets[MAX_STRIPS];
   L_INT StripSizes[MAX_STRIPS];
   L_INT nMaxIndex;
   DWORD wReadBytes;
  
   TempFileInfo.uStructSize = sizeof(TempFileInfo);
   nRet = L_FileInfo (szFileName, &TempFileInfo, sizeof(FILEINFO), 0, NULL);
   if(nRet != SUCCESS)
      return nRet;
  
  
   //******************************
   //*** L_StartDecompressBuffer
   //******************************
   memset(&StartDecompressData, 0, sizeof(STARTDECOMPRESSDATA) );
   memset(&DecompressData, 0, sizeof(DECOMPRESSDATA) );
  
   StartDecompressData.uStructSize = sizeof(STARTDECOMPRESSDATA);
   StartDecompressData.pBitmap = &Bitmap;
   StartDecompressData.uBitmapStructSize = sizeof(BITMAPHANDLE);
   StartDecompressData.uStripsOrTiles = DECOMPRESS_STRIPS;
   StartDecompressData.uFormat = FILE_RAW_PACKBITS;
   StartDecompressData.nWidth = TempFileInfo.Width;           
   StartDecompressData.nHeight = TempFileInfo.Height;         
   StartDecompressData.nBitsPerPixel = TempFileInfo.BitsPerPixel;   
   StartDecompressData.nViewPerspective = TempFileInfo.ViewPerspective;
   StartDecompressData.nRawOrder = TempFileInfo.Order;          
   StartDecompressData.nLoadOrder = ORDER_BGRORGRAY;
   StartDecompressData.nXResolution = TempFileInfo.XResolution;
   StartDecompressData.nYResolution = TempFileInfo.YResolution;
   StartDecompressData.pfnReadCallback = NULL;
   StartDecompressData.uFlags = 0;         
   StartDecompressData.pUserData = NULL;      
     
   StartDecompressData.nPhotoInt = 2;              // TIFF tag  0-6  WhiteIsZero(0) BlackIsZero(1) RGB(2)
  
   nRet = L_StartDecompressBuffer(&hDecompress, &StartDecompressData);
   if(nRet != SUCCESS)
      return nRet;
  
   //******************************
   //*** L_DecompressBuffer
   //******************************
  
   nMaxIndex = ReadTag(szFileName, TAG_STRIPOFFSETS,    StripOffsets);
   ReadTag(szFileName, TAG_STRIPBYTECOUNTS, StripSizes);
   ReadTag(szFileName, TAG_ROWSPERSTRIP, &nRowsPerStrip);
  
   fd = CreateFile(szFileName, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
   DecompressData.nRow = 0;//Note--this field is ignored for strips
   for (nIndex = 0; nIndex < nMaxIndex; nIndex++)
   {
      //seek to the first strip
      SetFilePointer(fd,StripOffsets[nIndex] , 0, FILE_BEGIN);
      pBuf = (L_UCHAR *)malloc(StripSizes[nIndex]);
      ReadFile (fd, pBuf, StripSizes[nIndex], &wReadBytes, NULL);
           
      DecompressData.uStructSize = sizeof(DECOMPRESSDATA);
      DecompressData.pBuffer = pBuf;                        //pointer to raw data
      DecompressData.nWidth = TempFileInfo.Width;           //Width of uncompressed strip/tile
      DecompressData.nHeight = nRowsPerStrip;               //Height of uncompressed strip/tile
      if (nIndex == (nMaxIndex - 1 ))
      {
         //fewer rows per strip
         DecompressData.nHeight = TempFileInfo.Height - (nMaxIndex - 1) * nRowsPerStrip;
      }
     
      DecompressData.uOffset = 0;                           //Offset of strip relative to buffer
      DecompressData.nBufferSize = StripSizes[nIndex];//Size of strip after compression
      DecompressData.nCol = 0;                              //Col offset of tile
      DecompressData.uFlags = DECOMPRESS_CHUNK_COMPLETE 
      DecompressData.nReserved1 = 0;                        //Reserved for future use
     
      nRet = L_DecompressBuffer ( hDecompress, &DecompressData);
      if(nRet != SUCCESS)
         return nRet;
     
      free(pBuf);
   }
  
   CloseHandle(fd);
  
   //******************************
   //*** L_StopDecompressBuffer
   //******************************
   L_StopDecompressBuffer (hDecompress);

   // Bitmap contains the uncompressed bitmap
   nRet = L_SaveBitmap (TEXT("C:\\Program Files\\LEAD Technologies\\LEADTOOLS 15\\Images\\Uncompressed.bmp"), &Bitmap, FILE_BMP, 24, 0, NULL);
   L_FreeBitmap(&Bitmap);
   return nRet;
}

Thank you!

Loretta :o)

Loretta,
The default behavior for LEADTOOLS when loading any type of image, including compressed TIFF, is to decompress it automatically.

This means an easy way to obtain a non-compressed buffer containing pixel data, is to simply load it, then get the data using L_GetBitmapRow().

The following code does this using LEADTOOLS 15:

BITMAPHANDLE Bitmap = {0};
int nBytes = 0;
L_UCHAR *pBuf = NULL; //pointer to buffer

L_LoadBitmap(TEXT("test.tif"), &Bitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGRORGRAY, NULL, NULL);
if(!Bitmap.Flags.Allocated) //loading failed
   return;

nBytes = Bitmap.BytesPerLine * BITMAPHEIGHT(&Bitmap);
pBuf = (L_UCHAR *)malloc(nBytes);

if(pBuf)
{
   L_AccessBitmap(&Bitmap);
   L_GetBitmapRow(&Bitmap, pBuf, 0, nBytes);

   //... DoSomthingWithBuffer(pBuf);

   free(pBuf);
   L_ReleaseBitmap(&Bitmap);
}
L_FreeBitmap(&Bitmap);

Does LEADTOOLS Load Method decompress all compression types? I have a program that fails to load files with LZW Compression.

Lucio Gayosso
Lead Developer, PCSS
lucio@pcssinc.com
l_gayosso@hotmail.com

Lucio,
You are already discussing this issue in the forum post below:
http://support.leadtools.com/SupportPortal/CS/forums/29706/ShowPost.aspx

Please continue discussing this issue in that forum post.