L_GrayScaleBitmap

#include "l_bitmap.h"

L_LTKRN_API L_INT L_GrayScaleBitmap(pBitmap, nBitsPerPixel)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_INT nBitsPerPixel;	/* number of bits */

Converts a 1-, 4-, 8-, 16-, 24-, or 32-bit bitmap to an 8-bit, 12-bit, 16-bit, or 32-bit grayscale bitmap. Support for 12, 16 and 32-bit grayscale images is available in the Document and Medical Imaging toolkits.

Parameter	Description
pBitmap	Pointer to the bitmap handle referencing the bitmap to be converted.
nBitsPerPixel	Value indicating the number of bits in the destination bitmap. Valid values are 8, 12, 16, or 32.

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 resulting bitmap can be an 8-bit, 12-bit, 16-bit or 32-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, 16-bit or 32-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.

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

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

Win32, x64.

See Also

Functions:	L_IsGrayScaleBitmap
Topics:	Raster Image Functions: Doing Color Expansion or Reduction
	Color Halftone and Halftone Images

Example

For complete sample code, refer to the FEATURE2 example. This example loads a bitmap and changes it to 8-bit grayscale.

#define MAKE_IMAGE_PATH(pFileName) TEXT("C:\\Users\\Public\\Documents\\LEADTOOLS Images\\")pFileName


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

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

   /* Change the bitmap to grayscale */
   nRet = L_GrayScaleBitmap(&LeadBitmap, 8 );
   if(nRet != SUCCESS)
      return nRet;

   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &LeadBitmap, FILE_BMP, 24, 0, NULL);
   if(nRet != SUCCESS)
      return nRet;

   L_FreeBitmap(&LeadBitmap);
   return SUCCESS;
}