L_CreateGrayScaleBitmap

#include "l_bitmap.h"

L_LTKRN_API L_INT L_CreateGrayScaleBitmap(pDstBitmap, pSrcBitmap,uBitsPerPixel)

pBITMAPHANDLE pDstBitmap;	/* pointer to the destination bitmap handle */
pBITMAPHANDLE pSrcBitmap;	/* pointer to the source bitmap handle */
L_INT uBitsPerPixel;	/* number of bits */

Converts a 1-, 4-, 8-, 16-, 24-, or 32-bit bitmap to an 8-bit, 12-bit, or 16-bit grayscale bitmap from an existing bitmap, and puts the grayed image into a destination bitmap.

Support for 12 and 16-bit grayscale images is only available in the Document and Medical Imaging toolkits.

Parameter	Description
pDstBitmap	Pointer to the bitmap handle referencing the destination bitmap to contain the new grayed image.
pSrcBitmap	Pointer to the bitmap handle referencing the source bitmap.
uBitsPerPixel	Value that indicates the number of bits in the destination bitmap. Valid values are 8, 12, or 16.

Returns

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

Comments

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.

The destination bitmap can be an 8-bit, 12-bit, or 16-bit grayscale bitmap. Once the function is complete, the Order member of the bitmap handle is set to ORDER_GRAY.

When converting to 12-bit or 16-bit grayscale, a Lookup table is not used. When converting to 8-bit grayscale, a Lookup table is used to get the RGB for each input pixel. The grayscale value corresponding to that RGB triple is used in the destination bitmap.

When converting to 12-bit or 16-bit grayscale, the function uses the LowBit and HighBit data stored in the destination bitmap structure. So the appropriate values for LowBit and HighBit in the destination bitmap structure, should be set before calling this function.

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

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.

Required DLLs and Libraries

LTKRN

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_IsGrayScaleBitmap, L_GrayScaleBitmap
Topics:	Raster Image Functions: Doing Color Expansion or Reduction
	Grayscale Images

Example

This example loads a bitmap and changes it to 16-bit grayscale.

 L_INT CreateGrayScaleBitmapExample(L_VOID)
{
   L_INT nRet;
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle to hold the loaded image. */
   BITMAPHANDLE DstBitmap;   /* Bitmap handle to hold the result image. */

   /* Load the bitmap, keeping the bits per pixel of the file */
   nRet = L_LoadBitmap (TEXT("%UserProfile%\\My Documents\\LEADTOOLS Images\\IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
   if(nRet != SUCCESS)
      return nRet;

   /* Change the bitmap to grayscale */
   DstBitmap.LowBit = 0;
   DstBitmap.HighBit = 15;
   nRet = L_CreateGrayScaleBitmap(&DstBitmap, &LeadBitmap, 16 );
   if(nRet != SUCCESS)
      return nRet;

   nRet = L_SaveBitmap(TEXT("%UserProfile%\\My Documents\\LEADTOOLS Images\\Result.BMP"), &DstBitmap, FILE_BMP, 24, 0, NULL);
   if(nRet != SUCCESS)
      return nRet;

   L_FreeBitmap(&LeadBitmap);
   L_FreeBitmap(&DstBitmap);
   return SUCCESS;
}