L_WindowLevel

#include "l_bitmap.h"

L_LTDIS_API L_INT L_WindowLevel(pBitmap, nLowBit, nHighBit, pLUT, ulLUTLength, uFlags)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_INT nLowBit;	/* low bit to use */
L_INT nHighBit;	/* high bit to use */
L_RGBQUAD* pLUT;	/* lookup table */
L_UINT ulLUTLength;	/* number of entries */
L_UINT uFlags;	/* flags */

Sets up the paint or paint and image processing functions' window leveling options for a specific 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 painted bitmap is 8-bit grayscale. If pLUT is not NULL, the painted bitmap is a 24-bit bitmap.
ulLUTLength	Value indicating the number of entries pointed to by pLUT. If pLUT is NULL, then set this to NULL too.
uFlags	Value indicating whether pLUT is used by the paint and image processing functions or only by the paint functions. Possible values are:
	Value	Meaning
	WINDOWLEVEL_PAINT	[0x00] pLUT is used only by the paint functions.
	WINDOWLEVEL_PAINT_AND_PROCESSING	[0x01] pLUT is used for both paint and image processing routines.

Returns

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

Comments

Provides "on demand" window-leveling for the paint functions and does not alter the image data. To convert the image data to a window-leveled bitmap, use L_WindowLevelBitmap.

This function is similar to L_WindowLevelExt, except that it uses 8-bit per component LUT instead of 16-bit per component LUT. The 16-bit LUT offers more precision than the 8-bit LUT, so it is better to use L_WindowLevelExt instead of L_WindowLevel.

The 16-bit and 8-bit LUTs are synchronized, which means the LUT applied by L_WindowLevelExt will change the LUT applied with L_WindowLevel and vice versa.

If WINDOW_LEVEL_PAINT_PROCESSING is specified, then all image processing functions will take the pLUT into account.

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

Required DLLs and Libraries

LTDIS

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 2000 / XP/Vista, Windows CE.

See Also

Functions:	L_WindowLevelExt, L_WindowLevelBitmap, L_WindowLevelBitmapExt, L_PaintDC, L_PaintDCBuffer, L_PaintDCEffect, L_PaintRgnDC, L_WindowLevelFillLUT, L_SelectBitmapData, L_ShiftBitmapData, L_AutoZoneBitmap
Topics:	Raster Image Functions: Palettes
	Raster Image Functions: Displaying and Printing
	Color Halftone and Halftone Images
	Grayscale Images
	Saving Window-Leveled Bitmaps
	Raster Image Functions: Processing an Image

Example

This example sets the window level values for painting and processing the bitmap with a custom palette.

L_INT WindowLevelExample(pBITMAPHANDLE pBitmap)
{
   L_INT nRet;
   L_UINT32 x;
   RGBQUAD* ptmp;
   RGBQUAD* pLUT;
   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);
   if(nRet != SUCCESS)
      return nRet;
   nRet = L_GetMinMaxVal(pBitmap, &nLow, &nHigh);
   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 */
   for(x=0;x<nSize/2;x++)
   {
      ptmp->rgbRed       = 255;
      ptmp->rgbGreen     = 0;
      ptmp->rgbBlue      = 0;
      ptmp->rgbReserved  = 0;
      ptmp++;
   }
   /* fill the rest with gray values */
   for(x=nSize/2;x<nSize;x++)
   {
      ptmp->rgbRed       = ((L_UCHAR) ((L_UINT32) (x - nLow) * 255 / (nHigh - nLow)));
      ptmp->rgbGreen     = ptmp->rgbRed;
      ptmp->rgbBlue      = ptmp->rgbGreen;
      ptmp->rgbReserved  = 0;
      ptmp++;
   }

   nRet = L_WindowLevel ( pBitmap, nLowBit, nHighBit,
      (RGBQUAD *)pLUT, nSize, WINDOWLEVEL_PAINT_AND_PROCESSING );
   if(nRet != SUCCESS)
      return nRet;

   GlobalFreePtr(pLUT);
   return SUCCESS;
}