#include "l_bitmap.h"

L_LTIMGEFX_API L_INT L_GetUserLookUpTable (pLookupTable, uLookupLen, apUserPoint, uUserPointCount, puPointCount, uFlags)

L_UINT *pLookupTable;

lookup table

L_UINT uLookupLen;

lookup table length

POINT *apUserPoint;

array of points

L_UINT uUserPointCount;

number of points in the array

L_UINT *puPointCount;

pointer to a variable to be updated

L_UINT32 uFlags;


Updates the lookup table, based on a curve that passes through the specified points.

Parameter Description
pLookupTable Pointer to the lookup table to be filled by this function. The length of the lookup table is specified in the uLookupLen parameter.
uLookupLen Length of the lookup table pointed to by the pLookupTable parameter. Possible values are:
  Value Meaning
  65536 16-bit / sample image
  4096 12-bit / sample image
  256 8-bit / sample image
apUserPoint Pointer to an array of POINT structures that contain the points on the curve used to update the lookup table.
uUserPointCount Number of points in the apUserPoint array.
puPointCount Pointer to a variable to be updated with the number of entries in the lookup table that were actually updated.
uFlags Reserved for future use. Must be 0.



The function was successful.

< 1

An error occurred. Refer to Return Codes.


This function will update the lookup table array using the best curve that passes through the points specified in the apUserPoint parameter. The points in the array may be sorted or not. In most cases, this function is used with the L_RemapBitmapIntensity 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_GetFunctionalLookupTable, L_RemapBitmapIntensity, L_AdjustBitmapTint, L_GammaCorrectBitmapExt


Changing Brightness and Contrast


Raster Image Functions: Changing Brightness and Contrast


Raster Image Functions: Modifying Intensity Values


This example will brighten the loaded bitmap using the lookup table updated by the L_GetUserLookUpTable function.

L_INT GetUserLookUpTableExample(L_VOID) 
   L_INT nRet; 
   L_UINT  LookupTable[256];  /* Array to hold lookup table*/ 
   BITMAPHANDLE LeadBitmap;  /*Bitmap handle to hold the loaded image */ 
   POINT  apUserPoint[3] = {{0,0},{128,150},{255,255}}; 
   /* Load the bitmap, force 24 bits per pixel */ 
   nRet = L_LoadBitmap (MAKE_IMAGE_PATH(TEXT("ImageProcessingDemo\\Image3.cmp")), &LeadBitmap, sizeof(BITMAPHANDLE), 24, ORDER_BGR, NULL, NULL);  
   if(nRet !=SUCCESS) 
      return nRet; 
   /*Get Lookup table where the array effected by user data function */ 
   nRet = L_GetUserLookUpTable (LookupTable, 256,apUserPoint, 3, NULL, 0); 
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet = L_RemapBitmapIntensity (&LeadBitmap, (L_INT *)LookupTable, 256,CHANNEL_MASTER);  
   if(nRet !=SUCCESS) 
      return nRet; 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &LeadBitmap, FILE_BMP, 24, 0, NULL); 
   if(nRet !=SUCCESS) 
      return nRet; 
   //free bitmap  
   return SUCCESS; 

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