LBitmap::GetUserLookupTable

#include "ltwrappr.h"

virtual L_INT LBitmap::GetUserLookupTable (pLookupTable, uLookupLen, apUserPoint, uUserPointCount, puPointCount)

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 */

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.

Returns

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

Comments

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 LBitmap::RemapIntensity function.

Required DLLs and Libraries

LTIMGEFX

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

See Also

Functions:	LBitmap::AdjustTint, LBitmap::GammaCorrectExt, LBitmap::GetFunctionalLookupTable, LBitmap::RemapIntensity
Topics:	Changing Brightness and Contrast
	Raster Image Functions: Modifying Intensity Values
	Raster Image Functions: Changing Brightness and Contrast

Example

L_INT LBitmap__GetUserLookupTableExample(LBitmap & Bitmap, L_TCHAR * pszFile)
{
   L_INT nRet;
   L_UINT LookupTable[256];
   POINT apUserPoint[3] = { {0, 0}, {128, 150}, {255, 255} };
   nRet =Bitmap.Load(pszFile, 24, ORDER_BGR);
   if(nRet !=SUCCESS)
      return nRet;
   nRet =Bitmap.GetUserLookupTable(LookupTable, 256, apUserPoint, 3, NULL);
   if(nRet !=SUCCESS)
      return nRet;
   nRet =Bitmap.RemapIntensity((L_INT*)LookupTable, 256, CHANNEL_MASTER);
   if(nRet !=SUCCESS)
      return nRet;
   return SUCCESS;
}