In This Topic ▼

LBitmap::WindowLevelBitmap

Summary

Converts a 12 or 16-bit grayscale image to an 8-bit grayscale or a 24-bit RGB bitmap.

Syntax

#include "ltwrappr.h"

virtual L_INT LBitmap::WindowLevelBitmap(nLowBit, nHighBit, pLUT, uLUTLength, nOrderDst, uFlags = 0)

Parameters

L_INT nLowBit

Value indicating the low bit used for leveling. 0 <= nLowBit <= nHighBit <= (11 for 12-bit grayscale or 15 for 16-bit grayscale).

L_INT nHighBit

Value indicating the high bit used for leveling. 0 <= nLowBit <= nHighBit <= (11 for 12-bit grayscale or 15 for 16-bit grayscale).

RGBQUAD * 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.

L_UINT uLUTLength

Value indicating the number of entries pointed to by pLUT.

L_INT nOrderDst

Value indicating the color order if the output bitmap will be 24-bit. If pLUT is NULL, this parameter is ignored. Possible values are:

Value	Meaning
ORDER_RGB	[0] The input colors are in red-green-blue order.
ORDER_BGR	[1] The input colors are in blue-green-red order.

L_UINT32 uFlags

Reserved for future use. Must be 0.

Returns

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

Comments

This function will convert the class object's bitmap to a window leveled bitmap. To implement window leveling without affecting the image, use LBitmap::WindowLevel.

The bitmap data is changed by this function.

This function supports 12 and 16-bit grayscale. Support for 12 and 16-bit grayscale images is available only in the Document/Medical toolkits.

This function supports signed data images.

LEADTOOLS supports two types of LUTs for 10-16-bit grayscale images (8-bit LUT and 16-bit LUT). Typical grayscale image display and processing is done using an 8-bit LUT. But, you can also use a 16-bit LUT, which offers more precision. Some special video cards and monitors also support display of grayscale images using a 16-bit LUT.

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

Window Level Function - Before

Window Level Function - After

View additional platform support for this Window Level function.

Required DLLs and Libraries

LTDIS
LTFIL
LTIMGCOR
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

Win32, x64.

Example

This example window levels the bitmap with a custom palette. The image data is changed in this example.

L_INT LBitmap__WindowLevelBitmapExample() 
{ 
   L_UINT32 x; 
   L_INT nLowBit; 
   L_INT nHighBit; 
   L_INT nLow; 
   L_INT nHigh; 
   L_UINT32 nSize; 
   RGBQUAD * ptmp; 
   RGBQUAD * pLUT; 
   LBitmap LeadBitmap; 
 
   /* Change the bitmap to 16-bit grayscale */ 
   LeadBitmap.GrayScale(16 ); 
 
   LeadBitmap.GetMinMaxBits(&nLowBit, &nHighBit); 
   LeadBitmap.GetMinMaxVal(&nLow, &nHigh); 
 
   nSize = (L_UINT32)(1L<<(nHighBit - nLowBit + 1)); 
   pLUT = (RGBQUAD *)GlobalAlloc(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++; 
   } 
 
   LeadBitmap.WindowLevel(nLowBit, nHighBit, 
                        (RGBQUAD *)pLUT, nSize, ORDER_BGR); 
 
   GlobalFreePtr(pLUT); 
 
   return SUCCESS; 
}