Enumerations
enum	TFFTNormalization { FFT_NORM_FWD = 1 , FFT_NORM_INV = 2 , FFT_NORM_SQRTN = 4 , FFT_NORM_NONE = 8 }
	Fourier Transform normalization. More...

enum	TFFTWindowing { FFT_WINDOW_NONE = 0 , FFT_WINDOW_HAMMING = 1 , FFT_WINDOW_BARTLETT = 2 , FFT_WINDOW_SEPARATEBARTLETT = 3 }
	Fourier Transform windowing. More...

Functions
cvbres_t	CreateFFTBandPassFilter (FFTImage ImageIn, float center1, float center2, float width, FFTImage &ImgOut)
	Generates a band pass filter in Fourier space. More...

cvbres_t	CreateFFTBandStopFilter (FFTImage ImageIn, float center1, float center2, float width, FFTImage &ImgOut)
	Generates a band stop filter in Fourier space. More...

cvbres_t	CreateFFTHighPassFilter (FFTImage ImageIn, float center, float width, FFTImage &ImgOut)
	Generates a high pass filter in Fourier space. More...

cvbres_t	CreateFFTLowPassFilter (FFTImage ImageIn, float center, float width, FFTImage &ImgOut)
	Generates a low pass filter in Fourier space. More...

cvbres_t	CVBImageToFFTImage (IMG ImageIn, FFTImage &ImgOut)
	The CVBImageToFFTImage function converts a CVB image with 2 planes to a FFTImage object. Plane 0 has to represent the real part of the image and plane 1 the imaginary part of the image. More...

cvbres_t	FFTFwd (IMG ImageIn, cvbdim_t left, cvbdim_t top, cvbdim_t right, cvbdim_t bottom, cvbdim_t Index, TFFTNormalization normalization, TFFTWindowing windowing, FFTImage &ImgOut)
	The FFTFwd function applies a forward Fast Fourier Transform to the input image (ImageIn). More...

cvbres_t	FFTImageToCVBImage (FFTImage ImageIn, IMG &ImgOut)
	The FFTImageToCVBImage function converts a FFTImage to a CVBImage with two planes so that the Image in Fourier space can be used as CVB Image. Plane 0 is the real part of the image and plane 1 is the imaginary part of the image. More...

cvbres_t	FFTImageToMagnitude (FFTImage ImageIn, IMG &ImgOut)
	The FFTImageToMagnitude function calculates the magnitude of elements of the source FFTImage (ImageIn). and returns a CVB Image (ImgOut) with magnitude values as float image. More...

cvbres_t	FFTImageToPhase (FFTImage ImageIn, IMG &ImgOut)
	The FFTImageToPhase function calculates the phase of elements of the source FFTImage (ImageIn). and returns a CVB Image (ImgOut) with phase values as float image. More...

cvbres_t	FFTInv (FFTImage ImageIn, TFFTNormalization normalization, IMG &ImgOut)
	The FFTInv function applies a inverse Fast Fourier Transform to the input FFTImage (ImageIn). It needs a FFTImage as ImageIn and returns a CVB Image (ImgOut). More...

cvbres_t	MultiplyConjFFTImages (FFTImage Image1In, FFTImage Image2In, FFTImage &ImgOut)
	The MultiplyConjFFTImages function multiplies Image1In with the complex conjugate image of Image2In and returns the result as FFTImage (ImgOut) in Fourier space. If you need to access the image data of the output image in Fourier space you have to convert the FFTImage to a CVB Image in Fourier space with /ref FFTImageToCVBImage. To reconvert the image to a FFTImage use /ref CVBImageToFFTImage. More...

cvbres_t	MultiplyFFTImages (FFTImage Image1In, FFTImage Image2In, FFTImage &ImgOut)
	The MultiplyFFTImages function multiplies the two source images (Image1In) and (Image2In). and returns the result as FFTImage Object (ImgOut). If you need to access the image data of the output image in Fourier space you have to convert the FFTImage to a CVB Image in Fourier space with /ref FFTImageToCVBImage. To reconvert the image to a FFTImage use /ref CVBImageToFFTImage. More...

Detailed Description

Author: SKi

Version: 1.0.0.0

Since: 1.0.0.0 Finished implementation. (SKi, 01.02.2011)

Enumeration Type Documentation

◆ TFFTNormalization

enum TFFTNormalization

Fourier Transform normalization.

The results of computing the Fourier transform can be normalized by specifying the appropriate value of TFFTNormalization. This parameter sets up a pair of matched normalization factors to be used in forward and inverse transforms.

Enumerator
FFT_NORM_FWD	1/XY is used as Normalization in a Forward Transformation
FFT_NORM_INV	1/XY is used as Normalization in a Inverse Transformation
FFT_NORM_SQRTN	1/sqrt(XY) is used in Forward and Inverse Transformation
FFT_NORM_NONE	No Normalization is used.

◆ TFFTWindowing

enum TFFTWindowing

Fourier Transform windowing.

A window is a mathematical function by which pixel values are multiplied to prepare an image for the subsequent analysis. This procedure is often called 'windowing'. A suitable window function approaches zero towards the edges of the image avoiding strong distortions of spectral densities in the Fourier domain.

Enumerator
FFT_WINDOW_NONE	No Windowing function is used.
FFT_WINDOW_HAMMING	Hamming Windowing function is used.
FFT_WINDOW_BARTLETT	Bartlett Windowing function is used.
FFT_WINDOW_SEPARATEBARTLETT	Bartlett Windowing function applies the window function successively to the rows and then to the columns of the image.

Function Documentation

◆ CreateFFTBandPassFilter()

cvbres_t CreateFFTBandPassFilter	(	FFTImage	ImageIn,
		float	center1,
		float	center2,
		float	width,
		FFTImage &	ImgOut
	)

Generates a band pass filter in Fourier space.

The filter image can be used with MultiplyFFTImages or MultiplyConjFFTImages to Filter an image in Fourier space.

To access the Fourier data convert the FFTImage to a CVB Image using FFTImageToCVBImage.

Attention: Release ImgOut with ReleaseObject when it is no longer needed.

Parameters

[in]	ImageIn	Input `FFTImage` object (necessary to determine the actual size of the filter; if the size of the image to be filtered changes, the Fourier representation of the filter will need to be recalculated).
[in]	center1	Lower cutoff position of the filter relative to the range of frequencies (range [0...1]).
[in]	center2	Upper cutoff position of the filter relative to the range of frequencies (range [0...1]).
[in]	width	Width of the filter cutoff region (range [0...1]). Higher values may help reduce ring artifacts. When uncertain, use 0.1.
[out]	ImgOut	Fourier representation of the low pass filter defined by the`center` and `width` parameter.

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

◆ CreateFFTBandStopFilter()

cvbres_t CreateFFTBandStopFilter	(	FFTImage	ImageIn,
		float	center1,
		float	center2,
		float	width,
		FFTImage &	ImgOut
	)

Generates a band stop filter in Fourier space.

The filter image can be used with MultiplyFFTImages or MultiplyConjFFTImages to Filter an image in Fourier space.

To access the Fourier data convert the FFTImage to a CVB Image using FFTImageToCVBImage.

Attention: Release ImgOut with ReleaseObject when it is no longer needed.

Parameters

[in]	ImageIn	Input `FFTImage` object (necessary to determine the actual size of the filter; if the size of the image to be filtered changes, the Fourier representation of the filter will need to be recalculated).
[in]	center1	Lower cutoff position of the filter relative to the range of frequencies (range [0...1]).
[in]	center2	Upper cutoff position of the filter relative to the range of frequencies (range [0...1]).
[in]	width	Width of the filter cutoff region (range [0...1]). Higher values may help reduce ring artifacts. When uncertain, use 0.1.
[out]	ImgOut	Fourier representation of the low pass filter defined by the`center` and `width` parameter.

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

◆ CreateFFTHighPassFilter()

cvbres_t CreateFFTHighPassFilter	(	FFTImage	ImageIn,
		float	center,
		float	width,
		FFTImage &	ImgOut
	)

Generates a high pass filter in Fourier space.

The filter image can be used with MultiplyFFTImages or MultiplyConjFFTImages to Filter an image in Fourier space.

To access the Fourier data convert the FFTImage to a CVB Image using FFTImageToCVBImage.

Attention: Release ImgOut with ReleaseObject when it is no longer needed.

Parameters

[in]	ImageIn	Input `FFTImage` object (necessary to determine the actual size of the filter; if the size of the image to be filtered changes, the Fourier representation of the filter will need to be recalculated).
[in]	center	Cutoff position of the filter relative to the range of frequencies (range [0...1]).
[in]	width	Width of the filter cutoff region (range [0...1]). Higher values may help reduce ring artifacts. When uncertain, use 0.1.
[out]	ImgOut	Fourier representation of the low pass filter defined by the`center` and `width` parameter.

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

◆ CreateFFTLowPassFilter()

cvbres_t CreateFFTLowPassFilter	(	FFTImage	ImageIn,
		float	center,
		float	width,
		FFTImage &	ImgOut
	)

Generates a low pass filter in Fourier space.

The filter image can be used with MultiplyFFTImages or MultiplyConjFFTImages to Filter an image in Fourier space.

To access the Fourier data convert the FFTImage to a CVB Image using FFTImageToCVBImage.

Attention: Release ImgOut with ReleaseObject when it is no longer needed.

Parameters

[in]	ImageIn	Input `FFTImage` object (necessary to determine the actual size of the filter; if the size of the image to be filtered changes, the Fourier representation of the filter will need to be recalculated).
[in]	center	Cutoff position of the filter relative to the range of frequencies (range [0...1]).
[in]	width	Width of the filter cutoff region (range [0...1]). Higher values may help reduce ring artifacts. When uncertain, use 0.1.
[out]	ImgOut	Fourier representation of the low pass filter defined by the`center` and `width` parameter.

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

◆ CVBImageToFFTImage()

cvbres_t CVBImageToFFTImage	(	IMG	ImageIn,
		FFTImage &	ImgOut
	)

The CVBImageToFFTImage function converts a CVB image with 2 planes to a FFTImage object. Plane 0 has to represent the real part of the image and plane 1 the imaginary part of the image.

Attention: Release the Output Image ImgOut with ReleaseObject when it is no longer needed to decrement the reference counter.

Parameters

[in]	ImageIn	Input image with 2 planes in Fourier space
[out]	ImgOut	Output FFTImage in Fourier space

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

◆ FFTFwd()

cvbres_t FFTFwd	(	IMG	ImageIn,
		cvbdim_t	left,
		cvbdim_t	top,
		cvbdim_t	right,
		cvbdim_t	bottom,
		cvbdim_t	Index,
		TFFTNormalization	normalization,
		TFFTWindowing	windowing,
		FFTImage &	ImgOut
	)

The FFTFwd function applies a forward Fast Fourier Transform to the input image (ImageIn).

It returns a FFTImage Object which represents the ImageIn in Fourier space. The FFTImage uses a compressed representation that makes use of the hermitian symmetries present in the FFT of a real-valued input image. A consequence of this is that the FFTImage objects cannot be displayed directly - use FFTImageToMagnitude and FFTImageToPhase to get a comprehensible visual representation of the fourier transform results.

The FFTImage objects can, however, be fed directly to the multiplication functions MultiplyFFTImages and MultiplyConjFFTImages, which are of particular interest for building Fourier-based filters.

To get direct access to the Fourier representation of the image, use FFTImageToCVBImage and CVBImageToFFTImage.

Attention: The FFTImage object ImgOut should be released using ReleaseObject when it is no longer needed.

Parameters

[in]	ImageIn	Object handle of the source image to be used.
[in]	left	Left edge of the area of interest.
[in]	top	Top edge of the area of interest.
[in]	right	Right edge of the area of interest.
[in]	bottom	Bottom edge of the area of interest.
[in]	Index	Plane of the input image to undergo transformation
[in]	normalization	Normalization to be used, taken from the TFFTNormalization enum. When uncertain use FFT_NORM_SQRTN.
[in]	windowing	Windowing to be used, taken from the TFFTWindowing enum.
[out]	ImgOut	Compressed Fourier space representation of the input image (`ImageIn`).

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

Examples:: CSharp - C# Foundation FFT Example Visual C++ - VC Foundation FFT Example Visual C++ - VC FFT Scaling Example

◆ FFTImageToCVBImage()

cvbres_t FFTImageToCVBImage	(	FFTImage	ImageIn,
		IMG &	ImgOut
	)

The FFTImageToCVBImage function converts a FFTImage to a CVBImage with two planes so that the Image in Fourier space can be used as CVB Image. Plane 0 is the real part of the image and plane 1 is the imaginary part of the image.

Attention: Release the Output Image ImgOut with ReleaseObject when it is no longer needed to decrement the reference counter.

Parameters

[in]	ImageIn	FFTImage Object in Fourier space
[out]	ImgOut	Output CVB Image in Fourier space

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

◆ FFTImageToMagnitude()

cvbres_t FFTImageToMagnitude	(	FFTImage	ImageIn,
		IMG &	ImgOut
	)

The FFTImageToMagnitude function calculates the magnitude of elements of the source FFTImage (ImageIn). and returns a CVB Image (ImgOut) with magnitude values as float image.

Attention: Release the Output Image ImgOut with ReleaseObject when it is no longer needed to decrement the reference counter.

Parameters

[in]	ImageIn	FFTImage Object in Fourier space
[out]	ImgOut	Object handle of the float output image.

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

◆ FFTImageToPhase()

cvbres_t FFTImageToPhase	(	FFTImage	ImageIn,
		IMG &	ImgOut
	)

The FFTImageToPhase function calculates the phase of elements of the source FFTImage (ImageIn). and returns a CVB Image (ImgOut) with phase values as float image.

Attention: Release the Output Image ImgOut with ReleaseObject when it is no longer needed to decrement the reference counter.

Parameters

[in]	ImageIn	FFTImage Object in Fourier space
[out]	ImgOut	Object handle of the float output image.

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

◆ FFTInv()

cvbres_t FFTInv	(	FFTImage	ImageIn,
		TFFTNormalization	normalization,
		IMG &	ImgOut
	)

The FFTInv function applies a inverse Fast Fourier Transform to the input FFTImage (ImageIn). It needs a FFTImage as ImageIn and returns a CVB Image (ImgOut).

Attention: Release the Output Image ImgOut with ReleaseObject when it is no longer needed to decrement the reference counter.

Parameters

[in]	ImageIn	FFTImage Object in Fourier space
[in]	normalization	Normalization to be used, taken from the TFFTNormalization enum Use `FFT_NORM_SQRTN` as default value
[out]	ImgOut	Object handle of the output image.

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

Examples:: CSharp - C# Foundation FFT Example Visual C++ - VC Foundation FFT Example Visual C++ - VC FFT Scaling Example

◆ MultiplyConjFFTImages()

cvbres_t MultiplyConjFFTImages	(	FFTImage	Image1In,
		FFTImage	Image2In,
		FFTImage &	ImgOut
	)

The MultiplyConjFFTImages function multiplies Image1In with the
complex conjugate image of Image2In and returns the result as FFTImage (ImgOut) in Fourier space. If you need to access the image data of the output image in Fourier space you have to convert the FFTImage to a CVB Image in Fourier space with /ref FFTImageToCVBImage. To reconvert the image to a FFTImage use /ref CVBImageToFFTImage.

Attention: Release the Output Image ImgOut with ReleaseObject when it is no longer needed to decrement the reference counter.

Parameters

[in]	Image1In	First FFTImage Object in Fourier space
[in]	Image2In	Second FFTImage Object in Fourier space
[out]	ImgOut	Output Image as FFTImage Object Can be Converted to a CVBImage with the function /ref FFTImageToCVBImage

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.

◆ MultiplyFFTImages()

cvbres_t MultiplyFFTImages	(	FFTImage	Image1In,
		FFTImage	Image2In,
		FFTImage &	ImgOut
	)

The MultiplyFFTImages function multiplies the two source images (Image1In) and (Image2In). and returns the result as FFTImage Object (ImgOut). If you need to access the image data of the output image in Fourier space you have to convert the FFTImage to a CVB Image in Fourier space with /ref FFTImageToCVBImage. To reconvert the image to a FFTImage use /ref CVBImageToFFTImage.

Attention: Release the Output Image ImgOut with ReleaseObject when it is no longer needed to decrement the reference counter.

Parameters

[in]	Image1In	First FFTImage Object in Fourier space
[in]	Image2In	Second FFTImage Object in Fourier space
[out]	ImgOut	Output Image as FFTImage Object Can be Converted to a CVBImage with the function /ref FFTImageToCVBImage

Returns: A value >= 0 indicates success. In case of an error, one of the values from CVCError.h is returned.


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Enumerations

Functions

Detailed Description

Enumeration Type Documentation

◆ TFFTNormalization

◆ TFFTWindowing

Function Documentation

◆ CreateFFTBandPassFilter()

◆ CreateFFTBandStopFilter()

◆ CreateFFTHighPassFilter()

◆ CreateFFTLowPassFilter()

◆ CVBImageToFFTImage()

◆ FFTFwd()

◆ FFTImageToCVBImage()

◆ FFTImageToMagnitude()

◆ FFTImageToPhase()

◆ FFTInv()

◆ MultiplyConjFFTImages()

◆ MultiplyFFTImages()