L_FTDisplayBitmap

#include "l_bitmap.h"

L_INT EXT_FUNCTION L_FTDisplayBitmap(pBitmap, pFTArray, uFlags)

pBITMAPHANDLE pBitmap;	/* pointer to the bitmap handle */
pFTARRAY pFTArray;	/* pointer to structure */
L_UINT uFlags;	/* flags */

This function is used to display the results of a Fast Fourier Transform or a Discrete Fourier analysis as a bitmap. This function is available in the Raster Pro and above toolkits.

Parameter	Description
pBitmap	Pointer to the bitmap handle that references the bitmap.
pFTArray	Pointer to a FTARRAY structure. The acxData member of the FTARRAY structure is a two-dimensional array holding the frequency components. Its dimensions must equal the bitmap dimensions.
uFlags	Flags that indicate the data to be shown and the plotting scale. You can use a bit-wise OR (\|) to specify one flag from each group.
	The following flags represent the data to be shown:
	Value	Meaning
	DSP_FT_MAG	[0x0001] Plot harmonics magnitude data.
	DSP_FT_PHS	[0x0002] Plot harmonics phase data.
	The following flags represent the plotting scale. These are ignored when DSP_FT_PHS is set:
	Value	Meaning
	DSP_FT_NORM	[0x0010] Plot harmonics magnitudes using the normal linear scale.
	DSP_FT_LOG	[0x0020] Plot harmonics magnitudes using logarithmic scale.

Returns

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

Comments

This function converts the acxData member of the FTARRAY structure computed by L_FFTBitmap or L_DFTBitmap functions into a bitmap. The resulting bitmap may be displayed such that it shows either the frequency harmonics amplitude data or phase data. The (0,0) frequency located in bitmap center, positive X harmonics in the right half and positive Y harmonics located in the lower half of the bitmap.

This function does not work on regions . If a bitmap has a region the function ignores it and processes the entire bitmap.

Bitmap should be allocated prior to calling this function. The size of the bitmap must be the same size as the bitmap that was used to generate acxData.

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

This function does not support 12 and 16-bit grayscale and 48 and 64-bit color images. If the image is 12 and 16-bit grayscale and 48 and 64-bit color, the function will not return an error.

This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

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_FFTBitmap, L_DFTBitmap, L_FrqFilterBitmap, L_FrqFilterMaskBitmap, L_AverageFilterBitmap, L_MedianFilterBitmap, L_AddBitmapNoise, L_IntensityDetectBitmap, L_SpatialFilterBitmap, L_BinaryFilterBitmap, L_MaxFilterBitmap, L_MinFilterBitmap, L_AddBitmapNoise, L_IntensityDetectBitmap, L_SpatialFilterBitmap, L_BinaryFilterBitmap, L_MaxFilterBitmap, L_MinFilterBitmap, L_AddShadowBitmap, L_ChangeHueSatIntBitmap, L_ColorThresholdBitmap, L_DFTBitmap, L_AllocFTArray, L_DirectionEdgeStatisticalBitmap, L_FFTBitmap, L_FreeFTArray, L_FrqFilterMaskBitmap, L_FTDisplayBitmap, L_GetBitmapStatisticsInfo, L_GetFeretsDiameter, L_GetObjectInfo, L_GetRgnContourPoints, L_GetRgnPerimeterLength, L_MathFunctionBitmap, L_RevEffectBitmap, L_SegmentBitmap, L_SubtractBackgroundBitmap, L_UserFilterBitmap, L_FragmentBitmap, L_HighPassFilterBitmap, L_UnsharpMaskBitmap
Topics:	Raster Image Functions: Fourier Transform
	Removing Noise

Example

/* This example loads a bitmap, applies the Discrete Fourier Transform function to it, and displays the data*/
RECT    rcRange;
BITMAPHANDLE LeadBitmap, DisplayBitmap; /* Bitmap handle to hold the loaded image. */
pFTARRAY  pFTArray;

/* Load the bitmap, keeping the bits per pixel of the file */
L_LoadBitmap(TEXT("IMAGE1.CMP"), &LeadBitmap, sizeof(BITMAPHANDLE), 0, ORDER_BGR, NULL, NULL);
L_CopyBitmap(&DisplayBitmap, &LeadBitmap, sizeof(BITMAPHANDLE));

/*Allocates buffer*/
L_AllocFTArray(&LeadBitmap, &pFTArray, sizeof(FTARRAY));

rcRange.left  = 0;
rcRange.right = LeadBitmap.Width / 4;
rcRange.top = 0;
rcRange.bottom = LeadBitmap.Height / 2;

/* apply DFT*/
L_DFTBitmap(&LeadBitmap, pFTArray, &rcRange, DFT_DFT | DFT_GRAY | DFT_RANGE| DFT_INSIDE_X| DFT_OUTSIDE_Y);

/*plot frequency magnitude*/
L_FTDisplayBitmap(&DisplayBitmap, pFTArray, DSP_FT_MAG | DSP_FT_LOG);

/*Frees buffer*/
L_FreeFTArray(pFTArray);