L_AddWeightedBitmaps

#include "l_bitmap.h"

L_INT EXT_FUNCTION L_AddWeightedBitmaps(pBitmap, uStructSize, hList, puFactor, uFlag)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_UINT uStructSize;	/* size of the BITMAPHANDLE structure */
HBITMAPLIST hList;	/* handle to the list of bitmaps */
L_UINT L_FAR * puFactor;	/* array of weight factors */
L_UINT uFlag;	/* operation flag */

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

Parameter	Description
pBitmap	Pointer to the bitmap handle that references the resulting bitmap.
uStructSize	Size in bytes, of the structure pointed to by pBitmap, for versioning. Use sizeof(BITMAPHANDLE).
hList	Handle to the list of bitmaps.
puFactor	Array of unsigned integer values that represent weights associated with the bitmaps in the specified list. Used only if uFlag is BC_ADDWEIGHTED or BC_AVGWEIGHTED.
uFlag	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

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.

If the value of uFlag parameter is:

$image\sqrblit.gif$ 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.

$image\sqrblit.gif$ BC_AVG, the function can be used to average several images. In this case, puFactor is ignored.

$image\sqrblit.gif$ 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.

$image\sqrblit.gif$ 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 only in the Document/Medical toolkits.

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

Required DLLs and Libraries

LTIMG

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

Windows 95 / 98 / Me, Windows 2000 / XP.

See Also

Example

/* This example creates a bitmap list from one loaded bitmap, rotating each copy by 72 degrees than others, then average them */

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 */
L_LoadBitmap (TEXT("IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);

/* Create and populate the bitmap list */
L_CreateBitmapList (&hList);
for (i = 0; i < 4; i++)
{
   L_CopyBitmap (&TmpBitmap, &LeadBitmap, sizeof(BITMAPHANDLE));
   L_RotateBitmap (&TmpBitmap, i*720, ROTATE_RESAMPLE, RGB(255, 0, 0));
   L_InsertBitmapListItem (hList, (L_UINT)-1, &TmpBitmap);
}

/*take the average between all rotated bitmaps, and put the result in the ResultBitmap */
L_AddWeightedBitmaps (&ResultBitmap, sizeof(BITMAPHANDLE), hList, NULL, BC_AVG);

L_FreeBitmap(&LeadBitmap);
L_DestroyBitmapList(hList);

Functions:	L_UnderlayBitmap, L_AddBitmaps, L_ChannelMix, L_DeinterlaceBitmap, L_DesaturateBitmap, L_EdgeDetectStatisticalBitmap, L_LightControlBitmap, L_SmoothEdgesBitmap, L_AutoColorLevelBitmap, L_ColorLevelBitmap, L_CorrelationBitmap, L_GrayScaleToDuotone, L_GrayScaleToMultitone, L_HolesRemovalBitmapRgn, L_SelectiveColorBitmap, L_SkeletonBitmap, L_BricksTextureBitmap, L_CanvasBitmap, L_DisplaceMapBitmap, L_FragmentBitmap, L_VignetteBitmap, L_AdjustBitmapTint, L_GammaCorrectBitmapExt, L_HighPassFilterBitmap, L_UnsharpMaskBitmap
Topics:	Raster Image Functions: Combining Images
	Raster Image Functions: Modifying Intensity Values
	Processing an Image
	Changing Brightness and Contrast
	Raster Image Functions: Changing Brightness and Contrast
	Removing Noise