LBitmap::RemapHue

#include "ltwrappr.h"

virtual L_INT LBitmap::RemapHue(pMask, pHTable, pSTable, pVTable, uLUTLen)

Uses a lookup table to change a bitmap's hue values. The saturation and value tables change S and V values only if a particular hue value is marked as non-zero in the pMask table. It is used for all resolutions, including 48 and 64-bit images. Support for 48 and 64-bit images is available only in the Document/Medical toolkits.

Returns

Comments

This function can be used to change a range of colors to another range of colors. For example, it could be used to change all red pixels to any color, where a red pixel can have any brightness (V) and any amount of white (saturation). A red pixel in this case would be

RGB(x,y,y) where

0<=x<(uLUTLen – 1) and 

0<=y<x

or in the HSV color space

HSV(0,x,x) where 

0<=x<=(uLUTLen – 1)

The pMask lookup table identifies which values in the pHTable are valid. If a pMask value is 0, then the corresponding value in the pHTable is ignored. If a pMask value is non-zero, then the corresponding value in the pHTable is used. For example, if a pixel has a hue value of 240 and pMask[240] is nonzero, then the hue value of 240 is replaced with pHTable[240]. Traditionally, hue ranges from 0 to 359. For the lookup table, the range of 0 to 359 is remapped to a range of 0.. uLUTLen – 1. For example, if uLUTLen = 256

To update a status bar or detect a user interrupt during execution of this function, refer to LBase::EnableStatusCallback.

This function supports 48 and 64-bit color images. Support for 48 and 64-bit color images is available only in the Document/Medical toolkits.

This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

Required DLLs and Libraries

See Also

Example

// The example uses the following macros: 
#define INCREMENT(x, uLUTLen) ((x+1)% uLUTLen) 
#define DECREMENT(x, uLUTLen) ((x+ (uLUTLen - 1))% uLUTLen) 
#define ADD(x,y, uLUTLen)     ((x+y)% uLUTLen) 
L_INT TestFunction(LBitmap * pBitmap, COLORREF crNewColor) 
{
   L_UINT  L_FAR * uMaskTable; 
   L_UINT  L_FAR * uHueTable; 
   L_UINT uHueGreen, uHueChange; 
   L_INT   iHueChange; 
   L_INT   i, iCount, nRet, uLUTLen; 
   if(pBitmap->GetBitsPerPixel() >= 48) 
      uLUTLen = 0x10000; 
   else if(pBitmap->IsGrayScale())
      uLUTLen = 256; 
   else if((pBitmap->GetHandle())->pLUT && (pBitmap->GetHandle())->Flags.UseLUT) 
      uLUTLen = 256; 
   else
      uLUTLen = (1 << pBitmap->GetBitsPerPixel ());
   //Allocate tables
   uMaskTable = (L_UINT *)malloc (uLUTLen * sizeof(L_UINT)); 
   uHueTable  = (L_UINT *)malloc (uLUTLen * sizeof(L_UINT)); 

   //Initialize tables
   for (i=0; i<uLUTLen; i++)
   {
      uMaskTable[i] = 0; 
      uHueTable[i] = i; 
   }

   //Get the hue for green
   uHueGreen = RGB(0,255,0); 

   //Obtain new hue
   iHueChange = (L_INT)RGB(0,255,0) - (L_INT)uHueGreen; 
   uHueChange = (iHueChange>0) ? (L_UINT)iHueChange : (L_UINT)(iHueChange + (uLUTLen - 1)); 
   uHueGreen   *= (uLUTLen - 1)/255; 
   uHueChange *= (uLUTLen - 1)/255; 

   //Set values in uHueTable, uMaskTable 
   uHueTable[uHueGreen] = (uHueTable[uHueGreen] + uHueChange); 
   uMaskTable[uHueGreen] = 1; 
   
   //set the hues near green (+/- 15) 
   iCount = (15 * (uLUTLen - 1))/255; 
   for (i=INCREMENT(uHueGreen,uLUTLen); iCount > 0; i = INCREMENT(i, uLUTLen), iCount--)
   {
      uHueTable[i] = ADD(uHueTable[i], uHueChange, uLUTLen); 
      uMaskTable[i] = 1; 
   }
  iCount = (15 * (uLUTLen - 1))/255; 
   for (i=DECREMENT(uHueGreen, uLUTLen); iCount > 0; i =DECREMENT(i, uLUTLen), iCount--)
   {
      uHueTable[i] = ADD(uHueTable[i],uHueChange, uLUTLen); 
      uMaskTable[i] = 1; 
   }
   
   nRet = pBitmap->RemapHue(uMaskTable, uHueTable, NULL, NULL, uLUTLen); 
   
   if(uMaskTable) 
      free(uMaskTable); 
   if(uHueTable) 
      free (uHueTable); 
   return nRet; 
}