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L_AddWeightedBitmaps

Summary

Adds or averages the bitmaps in a list according to their weight factors.

Syntax

#include "l_bitmap.h"

L_LTIMGCLR_API L_INT L_AddWeightedBitmaps(pBitmap, uStructSize, hList, puFactor, uFlags)

Parameters

pBITMAPHANDLE pBitmap

Pointer to the bitmap handle that references the resulting bitmap.

L_UINT uStructSize

Size in bytes, of the structure pointed to by pBitmap, for versioning. Use sizeof(BITMAPHANDLE).

L_UINT *puFactor

Array of unsigned integer values that represent weights associated with the bitmaps in the specified list. Used only if uFlags is BC_ADDWEIGHTED or BC_AVGWEIGHTED.

L_UINT uFlags

Flag that indicates the operation to perform. Possible values are:

Value	Meaning
BC_AVG	[0x0001] Average the bitmaps in the specified list.
BC_ADD	[0x0002] Add the bitmaps in the specified list.
BC_AVGWEIGHTED	[0x0003] Average the bitmaps in the specified list, according to the array of weight factors, `puFactor`.
BC_ADDWEIGHTED	[0x0004] Add the bitmaps in the specified list, according to the array of weight factors, puFactor.

Returns

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

Comments

This function can be used to modify the brightness (with the add operations) or remove the noise (with the average operations). Typically, you would call this function for a series of images taken of the same object at short intervals.

The sign flag in the BITMAPHANDLE structure must be the same for all images listed. That is, all hList images must be either signed or unsigned.

If the value of uFlags parameter is:

BC_ADD, the function can be used to add several images of the same view to improve the lightness or brightness of the image. In this case, puFactor is ignored.
BC_AVG, the function can be used to average several images. In this case, puFactor is ignored.
BC_ADDWEIGHTED, the function can be used to obtain an image as the sum of several weighted images. Each bitmap in any position in the list has a corresponding weight factor in the same position in the puFactor array. The real values are the weight factors divided by 100. For example if a weight factor is 131 its real value is 1.31. If puFactor equals NULL, each bitmap has the same weight factor of 100 and the result is the same as for BC_ADD.
BC_AVGWEIGHTED, the function can eliminate random noise by performing a weighted average. Each bitmap in any position in the list has a corresponding weight factor in the puFactor array. The real values are the weight factors in the array divided by 100. The weighted sum will be divided by the sum of the weights. If puFactor equals NULL, each bitmap has the same weight factor of 100 and the result is the same as for BC_AVG.

This function performs operations between data byte-by-byte. An image can be any color resolution. The resulting image of this operation will be allocated in the pBitmap where it is internally copied from the first image in the list. The operations are performed based on the smallest width and height of the input images.

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.

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.

Add Weighted Bitmaps Function - Before

Add-Weighted-Bitmaps Function - After

View additional platform support for this Add-Weighted-Bitmaps 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

This example creates a bitmap list by making copies of one bitmap, and rotating each copy by 72 degrees from the orientation of the previous copy. Then the bitmaps are averaged together.

L_INT AddWeightedBitmapsExample(L_VOID) 
{ 
   L_INT nRet; 
   HBITMAPLIST hList;         /* Bitmap list */ 
   BITMAPHANDLE LeadBitmap;   /* Bitmap handle to hold the loaded image. */ 
   BITMAPHANDLE TmpBitmap;    /* Temporary bitmap for manipulating the list */ 
   BITMAPHANDLE ResultBitmap; /* Resulting bitmap */ 
   L_INT i;                   /* Loop counter */ 
 
   /* 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; 
 
   /* Create and populate the bitmap list */ 
   nRet = L_CreateBitmapList(&hList); 
   if (nRet != SUCCESS) 
      return nRet; 
 
   for (i = 0; i < 4; i++) 
   { 
      nRet = L_CopyBitmap(&TmpBitmap, &LeadBitmap, sizeof(BITMAPHANDLE)); 
      if (nRet != SUCCESS) 
         return nRet; 
 
      nRet = L_RotateBitmap(&TmpBitmap, i * 720, ROTATE_RESAMPLE, RGB(255, 0, 0)); 
      if (nRet != SUCCESS) 
         return nRet; 
 
      nRet = L_InsertBitmapListItem(hList, (L_UINT)-1, &TmpBitmap); 
      if (nRet != SUCCESS) 
         return nRet; 
   } 
 
   /*take the average between all rotated bitmaps, and put the result in the ResultBitmap */ 
   nRet = L_AddWeightedBitmaps(&ResultBitmap, sizeof(BITMAPHANDLE), hList, NULL, BC_AVG); 
   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; 
 
   //free bitmap 
   if (LeadBitmap.Flags.Allocated) 
      L_FreeBitmap(&LeadBitmap); 
 
   L_DestroyBitmapList(hList); 
 
   return SUCCESS; 
}