L_ConvertBitmapSignedToUnsigned

#include "l_bitmap.h"

L_INT EXT_FUNCTION L_ConvertBitmapSignedToUnsigned(pBitmap, uShift)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
L_UINT uShift;	/* shifting option */

Converts a signed bitmap to unsigned.

Parameter	Description
pBitmap	Pointer to the bitmap handle referencing the bitmap.
uShift	Flag that indicates how the shift will be done. Possible values are:
	Value	Meaning
	SHIFT_ZERO_TO_CENTER	[0x0000] Shift by 32768 (16-bit images) or by 2048 (12-bit images)
	SHIFT_MIN_TO_ZERO	[0x0001] Shift all image data to make minimum value in the image 0 and the maximum value to the maximum possible value (65535 for 16-bit, 4095 for 12-bit).
	SHIFT_NEG_TO_ZERO	[0x0002] Set all the negative pixels to 0 and leave the positive pixels unchanged. (Achieves the same result as L_ClearNegativePixels).
	SHIFT_RANGE_ONLY	[0x0003] Shift data by adding half the range to each pixel without changing bits outside the (LowBit-HighBit) range.
	SHIFT_RANGE_PROCESS_OUTSIDE	[0x0004] Shift data by adding half the range to each pixel and set to zero all bits outside the (LowBit-HighBit) range.

Returns

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

Comments

If the ELO_SIGNED flag has been set using LOADFILEOPTION, when a file is loaded, the bitmap may contain negative pixel values and LEADTOOLS will paint/process the image incorrectly. To use this bitmap correctly the negative pixels should be converted, if it contains negative pixels (if pBitmap->Flags.Signed is TRUE).

If the pBitmap->Flags.Signed is set to TRUE, this function will shift the color values in the Bitmap according to the uShift parameter.

The function will also update the MinVal and MaxVal members of the BITMAPHANDLE.

This function supersedes L_ClearNegativePixels.

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.

This function supports signed data images.

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

Functions:	L_ClearNegativePixels, L_ConvertBitmapUnsignedToSigned
Topics:	Processing an Image
	Raster Image Functions: Getting and Setting Pixel Values

Example

BITMAPHANDLE LeadBitmap; /* Bitmap handle to hold the loaded image. */
LOADFILEOPTION LoadFileOption;

/* enable negative pixels to be loaded from TIFF files */
L_GetDefaultLoadFileOption(&LoadFileOption, sizeof(LOADFILEOPTION));
LoadFileOption.Flags |= ELO_SIGNED;

/* Load the bitmap, keeping the bits per pixel of the file */
L_LoadBitmap (TEXT("IMAGE1.TIF"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGRORGRAY, &LoadFileOption, NULL);

/* clear negative pixels if signed */
if(LeadBitmap.Flags.Signed)
L_ConvertBitmapSignedToUnsigned(&LeadBitmap, SHIFT_NEG_TO_ZERO);