MgenGabor

Board	Supported
Host System	Yes
V4L2	Yes
Clarity UHD	Yes
Concord PoE	No
GenTL	Yes
GevIQ	Yes
GigE Vision	Yes
Indio	No
Iris GTX	Yes
Radient eV-CL	Yes
Rapixo CL	Yes
Rapixo CoF	Yes
Rapixo CXP	Yes
USB3 Vision	Yes

Generate a Log-Gabor filter and its Hilbert transform.

Syntax

void MgenGabor(
    AIL_ID     ContextId,            //in
    AIL_ID     GaborDestId,          //out
    AIL_ID     HilbertDestId,        //out
    AIL_DOUBLE Param1,               //in
    AIL_DOUBLE Param2,               //in
    AIL_DOUBLE Param3,               //in
    AIL_DOUBLE Param4,               //in
    AIL_DOUBLE Param5,               //in
    AIL_INT    Normalization,        //in
    AIL_INT    DCComponentPosition,  //in
    AIL_INT    ControlFlag           //in
)

Description

This function generates a Log-Gabor filter and its Hilbert transformation using the following equation:

[Image: MgenGaborEquation.png]

This function writes the Log-Gabor filter and its Hilbert transformation to the specified image buffers in the frequency domain.

The Log-Gabor filter is useful for filtering out specific frequencies at a specified angle in images.

To apply the Log-Gabor filter to an image, the image must be in the frequency domain. You can perform a forward Fourier transform on an image, using MimTransform with M_FFT and M_FORWARD. You can apply the Log-Gabor filter to the transformed source image, using MimArith. Then, you can reverse the Fourier transform, using MimTransform with M_FFT and M_REVERSE, and display the filtered image.

Parameters

ContextId (in, AIL_ID)

Specifies the type of context.

GaborDestId (out, AIL_ID)

Specifies the identifier of the destination image buffer in which to write the Log-Gabor filter.

For specifying the image buffer in which to write the Log-Gabor filter

Value	Description
Image buffer identifier	Specifies the image buffer in which to write the Log-Gabor filter. The image buffer must be a 1-band, 32-bit processable float buffer.

HilbertDestId (out, AIL_ID)

Specifies the identifier of the destination image buffer in which to write the Hilbert transform of the Log-Gabor filter.

For specifying the image buffer in which to write the Hilbert transform

Value	Description
M_NULL	Specifies to not store the Hilbert transform in an image buffer.
Image buffer identifier	Specifies the image buffer in which to write the Hilbert transform. The image buffer must be a 1-band, 32-bit processable float buffer.

Param1 (in, AIL_DOUBLE)

Specifies the center orientation (_θ₀ _) of the Gabor filter.

Param2 (in, AIL_DOUBLE)

Specifies the center frequency (_f₀ _) of the Log-Gabor filter.

Param3 (in, AIL_DOUBLE)

Specifies the width parameter for the frequency (_σ_r _) of the Log-Gabor filter.

Param4 (in, AIL_DOUBLE)

Specifies the width parameter for the orientation (_σ_a _) of the Log-Gabor filter.

Param5 (in, AIL_DOUBLE)

Reserved for future use and must be set to M_NULL.

Normalization (in, AIL_INT)

Specifies the normalization factor applied to all values of the filters.

For specifying the Normalization factor

Value	Description
M_DEFAULT
M_DISABLE (default)	Specifies to not use a normalization factor.
M_NORMALIZE	Specifies to use a normalization factor. The normalization factor is defined as the SizeX multiplied by the SizeY of the image buffer specified by the GaborDestId parameter.

DCComponentPosition (in, AIL_INT)

Specifies the position of the DC Component.

For specifying the position of the DC component

Value	Description
M_DEFAULT
M_CENTER	Specifies that the DC component is located at the center.
M_TOP_LEFT (default)	Specifies that the DC component is located at the top left corner.

ControlFlag (in, AIL_INT)

Reserved for future use and must be set to M_DEFAULT.

Parameter Associations

For selecting the Gabor filter

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M_LOG_GABOR_FREQUENTIAL_CONTEXT_DEFAULT

Specifies a predefined Log-Gabor frequential filter context.

Value	Description
0.0 <= Value <= 180.0	Specifies the center angle.
0.0 < Value <= 0.75	Specifies the center frequency.
Value > 0.0	Specifies the width parameter for the frequency.
Value > 0.0	Specifies the width parameter for the orientation.