L_GetUserLookupTable

#include "l_bitmap.h"

L_INT EXT_FUNCTION L_GetUserLookupTable (pLookupTable, uLookupLen, apUserPoint, UserPointCount, puPointCount)

L_UINT L_FAR * pLookupTable;	/* lookup table */
L_UINT uLookupLen;	/* lookup table length */
POINT L_FAR *apUserPoint;	/* array of points */
L_UINT UserPointCount;	/* number of points in the array */
L_UINT L_FAR *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.
UserPointCount	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 L_RemapBitmapIntensity function.

Required DLLs and Libraries

LTIMG

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

Platforms

Windows 95 / 98 / Me, Windows 2000 / XP.

See Also

Functions:	L_GetFunctionalLookupTable, L_RemapBitmapIntensity, L_AdjustBitmapTint, L_GammaCorrectBitmapExt
Topics:	Changing Brightness and Contrast
	Raster Image Functions: Changing Brightness and Contrast
	Raster Image Functions: Modifying Intensity Values

Example

/* This example will brighten the loaded bitmap using the lookup table updated by the L_GetUserLookupTable function.*/

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 */
L_LoadBitmap (TEXT("IMAGE3.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 24, ORDER_BGR, NULL, NULL);
/*Get Lookup table where the array effected by user data function */
L_GetUserLookUpTable (LookupTable, 256,apUserPoint, 3, NULL);
L_RemapBitmapIntensity (&LeadBitmap, LookupTable, 256,CHANNEL_MASTER);