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


#include "l_bitmap.h"

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


L_UINT *pLookupTable

Pointer to the lookup table to be filled by this function. The length of the lookup table is specified in the uLookupLen parameter.

L_UINT 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

POINT *apUserPoint

Pointer to an array of POINT structures that contain the points on the curve used to update the lookup table.

L_UINT uUserPointCount

Number of points in the apUserPoint array.

L_UINT *puPointCount

Pointer to a variable to be updated with the number of entries in the lookup table that were actually updated.

L_UINT32 uFlags

Reserved for future use. Must be 0.


Value Meaning
SUCCESS 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


Win32, x64, Linux.

See Also




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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LEADTOOLS Raster Imaging C API Help

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© 1991-2022 LEAD Technologies, Inc. All Rights Reserved.