#include "l_bitmap.h"

L_LTIMGCOR_API L_INT L_WindowLevelBitmap (pBitmap, nLowBit, nHighBit, pLUT, uLUTLength, nOrderDst, uFlags)


pointer to the bitmap handle

L_INT nLowBit;

low bit to use

L_INT nHighBit;

high bit to use


lookup table

L_UINT uLUTLength;

number of entries

L_INT nOrderDst;

destination color order

L_UINT32 uFlags;


Converts a 12 or 16-bit grayscale image to an 8-bit grayscale or a 24-bit RGB bitmap.

Parameter Description
pBitmap Pointer to the bitmap handle referencing the bitmap to be leveled.
nLowBit Value indicating the low bit used for leveling. 0 <= nLowBit <= nHighBit <= (11 for 12-bit grayscale or 15 for 16-bit grayscale).
nHighBit Value indicating the high bit used for leveling. 0 <= nLowBit <= nHighBit <= (11 for 12-bit grayscale or 15 for 16-bit grayscale).
pLUT Optional lookup table that can be used to implement a user defined conversion. For every intensity value between 0 and 2 raised to the power of (nHighBit - nLowBit + 1) - 1 there should be a corresponding entry in the lookup table that contains an RGB quad. If pLUT is NULL, the conversion is a normal shift (right or left) and the output bitmap is 8-bit grayscale. If pLUT is not NULL, the output bitmap is a 24-bit bitmap.
uLUTLength Value indicating the number of entries pointed to by pLUT.
nOrderDst Value indicating the color order if the output bitmap will be 24-bit. If pLUT is NULL, this parameter is ignored. Possible values are:
  Value Meaning
  ORDER_RGB [0] The input colors are in red-green-blue order.
  ORDER_BGR [1] The input colors are in blue-green-red order.
uFlags Reserved for future use. Must be 0.



The function was successful.

< 1

An error occurred. Refer to Return Codes.


This function will convert the bitmap to a window leveled bitmap. To implement window leveling without affecting the image, use L_WindowLevel.

The bitmap data is changed by this function.

This function supports 12 and 16-bit grayscale. Support for 12 and 16-bit grayscale images is available in the Document and Medical Imaging toolkits.

This function is similar to L_WindowLevelBitmapExt, except that it uses 8-bit per component LUT instead of 16-bit per component LUT. If more precision is desired, you can use L_WindowLevelBitmapExt instead of L_WindowLevelBitmap.

For information on saving bitmaps that have been window leveled, refer to Saving Window-Leveled Bitmaps.

LEADTOOLS supports two types of LUTs for 10-16-bit grayscale images (8-bit LUT and 16-bit LUT).  Typical grayscale image display and processing is done using an 8-bit LUT.  But, you can also use a 16-bit LUT, which offers more precision.  Some special video cards and monitors also support display of grayscale images using a 16-bit LUT.

This function does not support 32-bit grayscale images. It returns the error code ERROR_GRAY32_UNSUPPORTED if a 32-bit grayscale image is passed to this function.

Required DLLs and Libraries


For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.


Win32, x64, Linux.

See Also


L_WindowLevelBitmapExt, L_WindowLevel, L_WindowLevelFillLUT, L_ChangeHueSatIntBitmap, L_ColorReplaceBitmap, L_ColorThresholdBitmap, L_AdaptiveContrastBitmap, L_ApplyMathLogicBitmap, L_ColorIntensityBalance, L_ColorizeGrayBitmap, L_ContBrightIntBitmap, L_DigitalSubtractBitmap, L_DynamicBinaryBitmap, L_EdgeDetectEffectBitmap, L_FunctionalLightBitmap, L_MultiScaleEnhancementBitmap, L_SelectBitmapData, L_ShiftBitmapData, L_WindowLevelExt, L_WindowLevelFillLUTExt


Raster Image Functions: Palettes


Color Halftone and Halftone Images


Grayscale Images


Saving Window-Leveled Bitmaps


Raster Image Functions: Processing an Image


This example window levels the bitmap with a custom palette. The image data is changed in this example.

L_INT WindowLevelBitmapExample(pBITMAPHANDLE pBitmap) 
   /* Load an pass a 24-bit image */ 
   L_INT nRet; 
   L_UINT32 x; 
   RGBQUAD * ptmp; 
   L_INT nLowBit; 
   L_INT nHighBit; 
   L_INT nLow; 
   L_INT nHigh; 
   L_UINT32 nSize; 
   /* Change the bitmap to 16-bit grayscale */ 
   nRet = L_GrayScaleBitmap(pBitmap, 16 ); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet = L_GetMinMaxBits(pBitmap, &nLowBit, &nHighBit, 0); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet = L_GetMinMaxVal(pBitmap, &nLow, &nHigh, 0); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nSize = (L_UINT32)(1L<<(pBitmap->HighBit - pBitmap->LowBit + 1)); 
   pLUT = (RGBQUAD *)GlobalAllocPtr(GHND, nSize * sizeof(RGBQUAD)); 
   ptmp = pLUT; 
   /* fill the first half of the LUT with RED */ 
      ptmp->rgbRed       = 255; 
      ptmp->rgbGreen     = 0; 
      ptmp->rgbBlue      = 0; 
      ptmp->rgbReserved  = 0; 
   /* fill the rest with gray values */ 
      ptmp->rgbRed       = (( L_UCHAR) ((L_UINT32) (x - nLow) * 255 / (nHigh - nLow))); 
      ptmp->rgbGreen     = ptmp->rgbRed; 
      ptmp->rgbBlue      = ptmp->rgbGreen; 
      ptmp->rgbReserved  = 0; 
   nRet = L_WindowLevelBitmap ( pBitmap, nLowBit, nHighBit,(RGBQUAD *)pLUT, nSize, ORDER_BGR, 0); 
   if(nRet !=SUCCESS) 
      return nRet; 
   return SUCCESS; 

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