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L_PosterizeBitmap

Summary

Imposes a poster effect on a bitmap by quantizing the bitmap's colors to a specified number of color levels per plane. For example, two levels means two of red, two of green, and two of blue.

Syntax

#include "l_bitmap.h"

L_LTIMGCLR_API L_INT L_PosterizeBitmap(pBitmap, uLevels, uFlags)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle that references the bitmap to be affected.

L_UINT uLevels

The number of color levels to use. Valid values are 2 through 64.

Returns

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

Comments

As an example, two levels means two of red, two of green, and two of blue.

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

This function supports 12 and 16-bit grayscale and 48 and 64-bit color images. Support for 12 and 16-bit grayscale and 48 and 64-bit color images is available in the Document and Medical Imaging toolkits.

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.

This function posterizes the image data. If the image has a LUT, the function will work on the LUT, not the image data.

If the image has a LUT and you want to work on the image data, set the UseLUT Flag in the BITMAPHANDLE structure to FALSE. Then, after calling the function, reset the UseLUT flag to TRUE as follows:

pBitmap->Flags.UseLUT = FALSE; 
L_PosterizeBitmap(pBitmap, 6); 
pBitmap->Flags.UseLUT = TRUE;

Posterize Function - Before

Posterize Function - After

View additional platform support for this Posterize function.

Required DLLs and Libraries

LTIMGCLR
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

For complete sample code, refer to the CHILD.C module of the DEMO
example.
This example loads a bitmap and posterizes it.

L_INT PosterizeBitmapExample(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; 
   /* Apply a poster effect with six color levels per plane */ 
   nRet = L_PosterizeBitmap(&LeadBitmap, 6 , 0); 
   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; 
   if(LeadBitmap.Flags.Allocated) 
      L_FreeBitmap(&LeadBitmap); 
 
   return SUCCESS; 
}