Starts the resizing process.


#include "l_bitmap.h"

L_LTKRN_API L_INT L_StartResizeBitmap(pBitmap, nNewWidth, nNewHeight, nNewBits, pPalette, nColors, uFlags, pfnCallback, pCallbackData, ppResizeData)



Pointer to a bitmap handle.

L_INT nNewWidth

New width of the image.

L_INT nNewHeight

New height of the image.

L_INT nNewBits

Output bits per pixel. Use 0 for 8-bit grayscale. Possible values are: 0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 24, 32, 48 and 64.

L_RGBQUAD * pPalette

Pointer to the palette to dither to if nNewBits<= 8. Pass NULL to dither to the fixed palette or if no palette is required.

L_INT nColors

The number of entries in pPalette. This value is only valid if pPalette is not NULL.

L_UINT uFlags

Flags that indicate the color order of the image, the type of resizing and the type of dithering. Flags from the different categories can be combined, but two flags from the same category can not be combined. Possible values are:

Value Meaning
ColorRes flags
RES_ORDERRGB [0x00000000] RGB color.
RES_ORDERBGR [0x00000004] BGR color order.
RES_ORDERGRAY [0x00000080] 12 or 16-bit grayscale. 12 and 16-bit grayscale images are only supported in Document and Medical Imaging toolkits.
RES_ORDERROMM [0x00000800] ROMM color order. ROMM only supports 24 and 48-bit images.
RES_ORDERRGB565 [0x00004000] RGB 565 byte order.
Resize flags
RES_NORMAL [0x00000000] Normal resizing.
RES_RESAMPLE [0x00000010] Linear interpolation resizing slower than RES_NORMAL.
RES_BICUBIC [0x00000020] Bicubic interpolation resizing slower than RES_RESAMPLE.
Dithering flags
RES_NODITHERING [0x00000000] No Dithering
RES_FLOYDSTEINDITHERING [0x00010000] Floyd Stein Dithering.
RES_STUCKIDITHERING [0x00020000] Stucki Dithering.
RES_BURKESDITHERING [0x00030000] Burkes Dithering.
RES_SIERRADITHERING [0x00040000] Sierra Dithering.
RES_STEVENSONARCEDITHERING [0x00050000] Stevenson Arce Dithering.
RES_JARVISDITHERING [0x00060000] Jarvis Dithering.
RES_ORDEREDDITHERING [0x00070000] Ordered Dithering.
RES_CLUSTEREDDITHERING [0x00080000] Clustered Dithering.
RES_DITHERINGOPTIONS [0x00FF0000] Mask to find dither option.
RES_USELUTAFTERRESIZE [0x00001000] Internal flag.
RES_IGNORELUT [0x00002000] Internal flag.
RES_LOWHIGHBITVALID [0x00000002] Internal use only.


Pointer to an optional callback that is used to get the rows from pBitmap. Pass NULL to have LEADTOOLS call L_GetBitmapRow directly.

L_VOID *pCallbackData

Optional parameter to be passed to pfnCallback.

L_VOID ** ppResizeData

Pointer to a variable that will be updated with information needed to perform the resize. You need to pass this information to subsequent calls to L_GetResizedRowCol and L_StopResizeBitmap.


Value Meaning
SUCCESS The function was successful.
< 1 An error occurred. Refer to Return Codes.


The dithering flags are used when dithering is needed to produce the output bits per pixel. The interpolation usually requires that the input data be converted to 24-bit or 48-bit and then back to the desired bits per pixel. So some dithering might be required if the output bits/pixel are <= 8.

L_StartResizeBitmap starts the resizing process. This will be followed by calls to L_GetResizedRowCol to retrieve the resized data and by a call to L_StopResizeBitmap, to free the memory allocated in ppResizeData.

Required DLLs and Libraries


Win32, x64, Linux.

See Also




L_INT StartResizeBitmapExample(pBITMAPHANDLE pBitmap,L_INT  nWidth,L_INT  nHeight) 
   L_VOID*        pResizeData; 
   L_INT          nRet; 
   L_UCHAR*       pBuffer; 
   BITMAPHANDLE   Bitmap; 
   L_INT          nRow=0; 
   L_INT          nCol=0; 
   nRet = L_StartResizeBitmap(pBitmap, 
                              NULL, // no palette 
                              RES_BICUBIC|RES_ORDERBGR, // bicubic interpolation, BGR order 
                              NULL,    // no callback 
                              NULL,    // no user data 
   if(nRet != SUCCESS) 
      return nRet; 
   nRet = L_CreateBitmap(&Bitmap, sizeof(BITMAPHANDLE), TYPE_CONV, nWidth, nHeight, 24, ORDER_BGR, NULL, 
                  pBitmap->ViewPerspective, NULL, 0); 
   if(nRet != SUCCESS) 
      return nRet; 
   pBuffer = (L_UCHAR *)GlobalAllocPtr(GMEM_MOVEABLE, Bitmap.BytesPerLine); 
      return nRet; 
   // get the rows for the resized image, one by one 
   for(nRow = 0; nRow < Bitmap.Height; nRow++) 
      nRet = L_GetResizedRowCol(pResizeData, pBuffer, nRow, 0, Bitmap.BytesPerLine); 
      if(nRet != SUCCESS) 
      L_PutBitmapRowCol(&Bitmap, pBuffer, nRow, nCol, Bitmap.BytesPerLine); 
   if(nRet == SUCCESS) 
      L_CopyBitmap(pBitmap, &Bitmap, sizeof(BITMAPHANDLE)); 
   return nRet; 
Help Version 22.0.2023.7.11
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LEADTOOLS Raster Imaging C API Help

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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.