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L_WindowLevelBitmap

Summary

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

Syntax

#include "l_bitmap.h"

L_LTIMGCOR_API L_INT L_WindowLevelBitmap (pBitmap, nLowBit, nHighBit, pLUT, uLUTLength, nOrderDst, uFlags)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle referencing the bitmap to be leveled.

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).

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 output bitmap is 8-bit grayscale. If pLUT is not NULL, the output 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 bitmap to a window leveled bitmap. To implement window leveling without affecting the image, use L_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 in the Document and Medical Imaging toolkits.

This function is similar to L_WindowLevelBitmapExt, except that it uses 8-bit per component LUT instead of 16-bit per component LUT. If more precision is desired, you can use L_WindowLevelBitmapExt instead of L_WindowLevelBitmap.

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

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.

This function does not support 32-bit grayscale images. It returns the error code ERROR_GRAY32_UNSUPPORTED if a 32-bit grayscale image is passed to this function.

Window Level Function - Before

Window Level Function - After

View additional platform support for this Window Level function.

Required DLLs and Libraries

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, Linux.

Example

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

L_INT WindowLevelBitmapExample(pBITMAPHANDLE pBitmap) 
{ 
   /* Load an pass a 24-bit image */ 
 
   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, 0); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   nRet = L_GetMinMaxVal(pBitmap, &nLow, &nHigh, 0); 
   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_WindowLevelBitmap(pBitmap, nLowBit, nHighBit, (RGBQUAD*)pLUT, nSize, ORDER_BGR, 0); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   GlobalFreePtr(pLUT); 
 
   return SUCCESS; 
}