#include "l_bitmap.h"

L_LTKRN_API L_INT L_GrayScaleBitmap(pBitmap, nBitsPerPixel)


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.




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


Value indicating the number of bits in the destination bitmap. Valid values are 8, 12, 16, or 32.



The function was successful.

< 1

An error occurred. Refer to Return Codes.


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


For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.


Win32, x64, Linux.

See Also




Raster Image Functions: Doing Color Expansion or Reduction


Color Halftone and Halftone Images


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

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; 
   return SUCCESS; 

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