L_ConvertBufferExt

#include "l_bitmap.h"

L_LTKRN_API L_INT L_ConvertBufferExt(pBuffer, nWidth, nBitsPerPixelSrc, nBitsPerPixelDst, nOrderSrc, nOrderDst, pPaletteSrc, pPaletteDst, uFlags, uLowBit, uHighBit)

L_UCHAR pBuffer;

pointer to the input buffer

L_INT nWidth;

image width, in pixels

L_INT nBitsPerPixelSrc;

input bits per pixel

L_INT nBitsPerPixelDst;

output bits per pixel

L_INT nOrderSrc;

input color order

L_INT nOrderDst;

output color order

L_RGBQUAD pPaletteSrc;

pointer to the palette for the existing data

L_RGBQUAD* pPaletteDst;

pointer to the palette for the converted data

L_UINT uFlags;

option flags

L_INT uLowBit;

low bit

L_INT uHighBit;

high bit

Converts data in the specified buffer to the specified bits per pixel and color order. You can convert from any bits per pixel to any bits per pixel.

Parameter Description
pBuffer Pointer to the input buffer.
nWidth Image width, in pixels.
nBitsPerPixelSrc Input bits per pixel. Possible values are 1, 2, 3, 4, 5, 6, 7, 8, 16, 24, 32, 48, and 64.
nBitsPerPixelDst Output bits per pixel. Use 0 for 8-bit grayscale.
nOrderSrc The input color order. Possible values are:
  Value Meaning
  ORDER_RGB [0] The input colors are in red-green-blue order.
  ORDER_BGR [1] The input colors are in blue-green-red order.
  ORDER_GRAY [2] The input is grayscale.
  ORDER_ROMM [5] The input colors are in ROMM order. ROMM only supports 24 and 48-bit images.
  0 The data is 8 bits per pixel or less.
nOrderDst The output color order. Possible values are:
  Value Meaning
  ORDER_RGB [0] The output colors are in red-green-blue order.
  ORDER_BGR [1] The output colors are in blue-green-red order.
  ORDER_GRAY [2] The output is grayscale.
  ORDER_ROMM [5] The output colors are in ROMM order. ROMM only supports 24 and 48-bit images.
  0 The data is 8 bits per pixel or less.
pPaletteSrc Pointer to the palette for the existing data, before conversion. If the data is converted from 16 or 24 bits per pixel, use NULL for no palette.
pPaletteDst Pointer to the palette for the converted data. If the data is converted to 16 or 24 bits per pixel color, use NULL for no palette.
uFlags Flags indicating whether to treat 16 bit data as grayscale or color. Possible values are:
  Value Meaning
  CVT_SRCGRAY [0x0001] Source buffer has grayscale data.
  CVT_DSTGRAY [0x0002] Destination buffer has grayscale data.
  CVT_SRCUSEBITS [0x0003] uLowBit and uHighBit apply to the source bitmap.
  CVT_SRCDSTBITS [0x0004] uLowBit and uHighBit apply to the destination bitmap.
  CVT_DSTUSEBITS [0x0008] uLowBit and uHighBit apply to the destination bitmap.
  CVT_USEALPHA [0x0010] Use the alpha channel data (if present).
  CVT_ALPHAINIT [0x0020] Initialize the alpha channel (for 32 or 64-bit color images) to all ones (0xFF for 8-bit alpha channels and 0xFFFF for 16-bit alpha channels).  Without this flag, a created alpha channel initializes to zeros.
CVT_SIGNED [0x0100] Treat image data as signed data during conversion.
uLowBit Value indicating the low bit in the source buffer, if the source buffer contains grayscale data.
uHighBit Value indicating the high bit in the source buffer, if the source buffer contains grayscale data.

Returns

SUCCESS

The function was successful.

< 1

An error occurred. Refer to Return Codes.

Comments

Note: This function will also work for 12, 16 and 32-bit grayscale images, but only in the Document and Medical Imaging toolkits. If you attempt to use this function with a 12, 16 or 32-bit grayscale image, but you do not have a Medical Imaging edition, you will receive an error.

The conversion uses only one buffer, which must be large enough to hold the data before and after conversion.

Image data that is 8 bits per pixel or less must use a palette, and this function can use such data as input, output, or both. Therefore, you may need to specify the palette for the input, or for the output, or both.

If either nBitsPerPixelSrc or nBitsPerPixelDst is 16 or 32, uFlags is used to determine whether the data should be treated as color or grayscale.

If nBitsPerPixelSrc is 12, it is assumed to be grayscale. However, the uFlags parameter should also reflect that it is grayscale for future compatibility.

If the source is grayscale (other than 32-bit), pPaletteSrc can be set to a palette. The palette should contain N entries. If the source uses uLowBit and uHighBit, then N equals 2 raised to the power of (uHighBit - uLowBit + 1). Otherwise, N equals 2 raised to the power of nBitsPerPixelSrc. Note that if the source is 32-bit grayscale, the value of the pPaletteSrc parameter will be ignored

uFlags supersedes nOrderSrc and nOrderDst. If you specify ORDER_BGR for nOrderSrc, but use CVT_SRCGRAY in uFlags, it will be assumed that the source buffer contains grayscale data.

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, Linux.

See Also

Functions:

L_ConvertBuffer, L_ConvertBufferExt2

Topics:

Raster Image Functions: Doing Color Space Conversions

 

Raster Image Functions: Doing Color Expansion or Reduction

Example

This example loads a temporary bitmap at 24 bits per pixel, creates a new 16-bit grayscale image, and uses L_ConvertBuffer to convert data from the temporary bitmap to the new one.

L_INT ConvertBufferExtExample(HWND hWnd) 
{ 
   L_INT nRet; 
   BITMAPHANDLE   LeadBitmap; /* Bitmap handle for the final image */ 
   BITMAPHANDLE   TmpBitmap;  /* Bitmap handle to hold the input image */ 
   L_UCHAR*       pBuf;       /* Buffer to hold the row */ 
   HGLOBAL        hBuf;       /* Handle to the buffer */ 
   L_INT          i;          /* Loop counter */ 
   /* Load the bitmap, at 24 bits per pixel */ 
   nRet = L_LoadBitmap (MAKE_IMAGE_PATH(TEXT("ImageProcessingDemo\\Image3.cmp")), &TmpBitmap, sizeof(BITMAPHANDLE), 24, 0, NULL, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Create a new 16-bit grayscale bitmap */ 
   nRet = L_CreateBitmap(&LeadBitmap, sizeof(BITMAPHANDLE), TYPE_CONV, TmpBitmap.Width, TmpBitmap.Height, 
                  16, ORDER_GRAY, NULL, TmpBitmap.ViewPerspective, NULL, 0); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Allocate and lock the buffer */ 
   hBuf = GlobalAlloc(GMEM_MOVEABLE,max(LeadBitmap.BytesPerLine, TmpBitmap.BytesPerLine)); 
   pBuf = (L_UCHAR*)GlobalLock( hBuf ); 
   /* Process each row from TmpBitmap to LeadBitmap */ 
   L_AccessBitmap(&LeadBitmap); 
   L_AccessBitmap(&TmpBitmap); 
   
   for(i=0; i < TmpBitmap.Height; i++) 
   { 
      nRet =(L_INT) L_GetBitmapRow(&TmpBitmap, pBuf, i, TmpBitmap.BytesPerLine); 
      if(nRet < 1) 
         return nRet; 
      nRet = L_ConvertBufferExt(pBuf, TmpBitmap.Width,  
         TmpBitmap.BitsPerPixel, LeadBitmap.BitsPerPixel, 
         TmpBitmap.Order, LeadBitmap.Order, NULL, NULL, 
         CVT_DSTGRAY, 0, 15); 
      if(nRet != SUCCESS) 
         return nRet; 
      nRet = (L_INT )L_PutBitmapRow(&LeadBitmap, pBuf, i, LeadBitmap.BytesPerLine); 
      if(nRet < 1) 
         return nRet; 
   } 
   L_ReleaseBitmap(&LeadBitmap); 
   L_ReleaseBitmap(&TmpBitmap); 
   /* Free memory that we no longer need */ 
   GlobalUnlock(hBuf); 
   GlobalFree(hBuf); 
   nRet = L_SaveBitmap(MAKE_IMAGE_PATH(TEXT("Result.BMP")), &LeadBitmap, FILE_BMP, 24, 0, NULL); 
   if(nRet != SUCCESS) 
      return nRet; 
   /* Free the temporary bitmap */ 
   if(TmpBitmap.Flags.Allocated)   
      L_FreeBitmap(&TmpBitmap); 
   if(LeadBitmap.Flags.Allocated)   
      L_FreeBitmap(&LeadBitmap); 
   /* Force paint palette creation */ 
   SendMessage (hWnd, WM_QUERYNEWPALETTE, 0, 0L); 
   return SUCCESS; 
} 

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