Namespace for collection of filter functions from the Foundation package. More...

Enumerations
enum class	FixedFilterSize { Kernel3x3 = CExports::FM_3x3 , Kernel5x5 = CExports::FM_5x5 , Kernel7x7 = CExports::FM_7x7 }
	Filter size values for filters using a fixed or discrete sized kernel. More...

enum class	FilterOrientation { Horizontal , Vertical }
	Orientation options for edge filters. More...

enum class	EdgeFilter { Scharr = CExports::CE_Scharr , Sobel = CExports::CE_Sobel , Sobel2nd = CExports::CE_Sobel2nd }
	Edge filter modes. Currently only used by Canny(). More...

enum class	RobertsDirection { Up , Down }
	Directions of the Roberts edge filter. More...

Functions
std::unique_ptr< Image >	Canny (const ImagePlane &imagePlane, Filter::EdgeFilter edgeFilter, int lowerThreshold, int upperThreshold)
	Edge filter using the Canny algorithm. More...

std::unique_ptr< Image >	Laplace (const Image &image, Filter::FixedFilterSize size)
	This function applies a square high pass Laplace filter to an image. More...

std::unique_ptr< Image >	Sharpen (const Image &image)
	This function applies a Filter::FixedFilterSize::Kernel3x3 sharpen filter to an image. More...

std::unique_ptr< Image >	LowPass (const Image &image, Filter::FixedFilterSize size)
	This function applies a square low pass filter to an image. More...

std::unique_ptr< Image >	HighPass (const Image &image, Filter::FixedFilterSize size)
	This function applies a square high pass filter to an image. More...

std::unique_ptr< Image >	Gauss (const Image &image, Filter::FixedFilterSize size)
	This function applies a low high pass Gaussian filter to an image. More...

std::unique_ptr< Image >	BoxMean (const Image &image, Size2D< int > maskSize, Point2D< int > maskOffset)
	This function sets each pixel in the output image to the average of all the input image pixels in the rectangular neighborhood defined by the maskSize and the maskOffset parameters. More...

std::unique_ptr< Image >	BoxMean (const Image &image, Size2D< int > maskSize)
	This function sets each pixel in the output image to the average of all the input image pixels in the rectangular neighborhood defined by the maskSize parameter. More...

std::unique_ptr< Image >	BoxMin (const Image &image, Size2D< int > maskSize, Point2D< int > maskOffset)
	This function sets each pixel in the output image to the minimum value of all the input image pixels in the rectangular neighborhood defined by the maskSize and the maskOffset parameters. More...

std::unique_ptr< Image >	BoxMin (const Image &image, Size2D< int > maskSize)
	This function sets each pixel in the output image to the minimum value of all the input image pixels in the rectangular neighborhood defined by the maskSize parameter. More...

std::unique_ptr< Image >	BoxMax (const Image &image, Size2D< int > maskSize, Point2D< int > maskOffset)
	This function sets each pixel in the output image to the maximum value of all the input image pixels in the rectangular neighborhood defined by the maskSize and the maskOffset parameters. More...

std::unique_ptr< Image >	BoxMax (const Image &image, Size2D< int > maskSize)
	This function sets each pixel in the output image to the maximum value of all the input image pixels in the rectangular neighborhood defined by the maskSize parameter. More...

std::unique_ptr< Image >	BoxMedian (const Image &image, Size2D< int > maskSize, Point2D< int > maskOffset)
	This function sets each pixel in the output image to the median value of all the input image pixels in the rectangular neighborhood defined by the maskSize and the maskOffset parameters. More...

std::unique_ptr< Image >	BoxMedian (const Image &image, Size2D< int > maskSize)
	This function sets each pixel in the output image to the median value of all the input image pixels in the rectangular neighborhood defined by the maskSize parameter. More...

std::unique_ptr< Image >	ColorMedian (const Image &image, Filter::FixedFilterSize maskType)
	Apply a color-correct box median filter to an RGB image. More...

std::unique_ptr< Image >	Wiener (const Image &image, Size2D< int > maskSize, Point2D< int > maskOffset, double noiseThreshold=0.0)
	This function performs adaptive filtering of an image degraded by constant power additive noise. More...

std::unique_ptr< Image >	Wiener (const Image &image, Size2D< int > maskSize, double noiseThreshold=0.0)
	This function performs adaptive filtering of an image degraded by constant power additive noise. More...

std::unique_ptr< Image >	Prewitt (const Image &image, Filter::FilterOrientation orientation)
	Applies a Prewitt edge filter to the input image. More...

std::unique_ptr< Image >	Scharr (const Image &image, Filter::FilterOrientation orientation)
	Applies a Scharr edge filter to the input image. More...

std::unique_ptr< Image >	Sobel (const Image &image, Filter::FilterOrientation orientation, Filter::FixedFilterSize maskSize)
	Applies a Sobel edge filter to the input image. More...

std::unique_ptr< Image >	Sobel2nd (const Image &image, Filter::FilterOrientation orientation, Filter::FixedFilterSize maskSize)
	Applies a 2nd order Sobel edge filter to the input image. More...

std::unique_ptr< Image >	Sobel2ndCross (const Image &image, Filter::FixedFilterSize maskSize)
	Applies a 2nd order Sobel cross edge filter to the input image. More...

std::unique_ptr< Image >	Roberts (const Image &image, Filter::RobertsDirection direction)
	Apply a Roberts edge detector to the input image. More...

Detailed Description

Namespace for collection of filter functions from the Foundation package.

Remarks: CMake users: Link to imported target CVB::CvbFoundationFilter

Enumeration Type Documentation

◆ EdgeFilter

enum class EdgeFilter

strong

Edge filter modes. Currently only used by Canny().

Enumerator
Scharr	Scharr edge detection.
Sobel	1st order Sobel filter.
Sobel2nd	2nd order Sobel filter.

◆ FilterOrientation

enum class FilterOrientation

strong

Orientation options for edge filters.

Enumerator
Horizontal	Horizontal.
Vertical	Vertical.

◆ FixedFilterSize

enum class FixedFilterSize

strong

Filter size values for filters using a fixed or discrete sized kernel.

Please refer to the respective filter's documentation, as not all filters support all filter kernel sizes. Functions, that used fixed size filter masks, are implicitly always assuming the mask to be centered around the center pixel.

Enumerator
Kernel3x3	Filter mask 3x3 pixels.
Kernel5x5	Filter mask 5x5 pixels.
Kernel7x7	Filter mask 7x7 pixels.

◆ RobertsDirection

enum class RobertsDirection

strong

Directions of the Roberts edge filter.

Enumerator
Up	Filter for edges, that are positive when looking from the top right corner.
Down	Filter for edges, that are positive when looking from the top left corner.

Function Documentation

◆ BoxMax() [1/2]

std::unique_ptr< Image > BoxMax	(	const Image &	image,
		Size2D< int >	maskSize
	)

inline

This function sets each pixel in the output image to the maximum value of all the input image pixels in the rectangular neighborhood defined by the maskSize parameter.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

This has the effect of smoothing or blurring the input image. Mask offset is automatically set to the center of the mask rectangle.

◆ BoxMax() [2/2]

std::unique_ptr< Image > BoxMax	(	const Image &	image,
		Size2D< int >	maskSize,
		Point2D< int >	maskOffset
	)

inline

This function sets each pixel in the output image to the maximum value of all the input image pixels in the rectangular neighborhood defined by the maskSize and the maskOffset parameters.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.
[in]	maskOffset	Mask center pixel location.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

This has the effect of smoothing or blurring the input image.

◆ BoxMean() [1/2]

std::unique_ptr< Image > BoxMean	(	const Image &	image,
		Size2D< int >	maskSize
	)

inline

This function sets each pixel in the output image to the average of all the input image pixels in the rectangular neighborhood defined by the maskSize parameter.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

This has the effect of smoothing or blurring the input image. Mask offset is automatically set to the center of the mask rectangle.

◆ BoxMean() [2/2]

std::unique_ptr< Image > BoxMean	(	const Image &	image,
		Size2D< int >	maskSize,
		Point2D< int >	maskOffset
	)

inline

This function sets each pixel in the output image to the average of all the input image pixels in the rectangular neighborhood defined by the maskSize and the maskOffset parameters.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.
[in]	maskOffset	Mask center pixel location.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

This has the effect of smoothing or blurring the input image.

◆ BoxMedian() [1/2]

std::unique_ptr< Image > BoxMedian	(	const Image &	image,
		Size2D< int >	maskSize
	)

inline

This function sets each pixel in the output image to the median value of all the input image pixels in the rectangular neighborhood defined by the maskSize parameter.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

This has the effect of smoothing or blurring the input image. Mask offset is automatically set to the center of the mask rectangle.

◆ BoxMedian() [2/2]

std::unique_ptr< Image > BoxMedian	(	const Image &	image,
		Size2D< int >	maskSize,
		Point2D< int >	maskOffset
	)

inline

This function sets each pixel in the output image to the median value of all the input image pixels in the rectangular neighborhood defined by the maskSize and the maskOffset parameters.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.
[in]	maskOffset	Mask center pixel location.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

This has the effect of smoothing or blurring the input image.

◆ BoxMin() [1/2]

std::unique_ptr< Image > BoxMin	(	const Image &	image,
		Size2D< int >	maskSize
	)

inline

This function sets each pixel in the output image to the minimum value of all the input image pixels in the rectangular neighborhood defined by the maskSize parameter.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

This has the effect of smoothing or blurring the input image. Mask offset is automatically set to the center of the mask rectangle.

◆ BoxMin() [2/2]

std::unique_ptr< Image > BoxMin	(	const Image &	image,
		Size2D< int >	maskSize,
		Point2D< int >	maskOffset
	)

inline

This function sets each pixel in the output image to the minimum value of all the input image pixels in the rectangular neighborhood defined by the maskSize and the maskOffset parameters.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.
[in]	maskOffset	Mask center pixel location.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

This has the effect of smoothing or blurring the input image.

◆ Canny()

std::unique_ptr< Image > Canny	(	const ImagePlane &	imagePlane,
		Filter::EdgeFilter	edgeFilter,
		int	lowerThreshold,
		int	upperThreshold
	)

inline

Edge filter using the Canny algorithm.

Parameters

[in]	imagePlane	Image plane to be filtered.
[in]	edgeFilter	Edge filter method to be used.
[in]	lowerThreshold	Lower threshold for hysteresis thresholding.
[in]	upperThreshold	Upper threshold for edge detection and hysteresis thresholding.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

The algorithm uses three stages:

imagePlane is differentiated in x and y direction using the edgeFilter. From the two derivatives the direction and magnitude is computed.
The directional information is simplified and then the local maximum along an edge contour is determined that lies above the upperThreshold.
The contours are then traced starting from the local maximum using hysteresis thresholding with the lowerThreshold to counter broken edges.

◆ ColorMedian()

std::unique_ptr< Image > ColorMedian	(	const Image &	image,
		Filter::FixedFilterSize	maskType
	)

inline

Apply a color-correct box median filter to an RGB image.

Parameters

[in]	image	Image to apply the filter to.
[in]	maskType	Mask size to use.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

The input image must have an RGB color model.

◆ Gauss()

std::unique_ptr< Image > Gauss	(	const Image &	image,
		Filter::FixedFilterSize	size
	)

inline

This function applies a low high pass Gaussian filter to an image.

Parameters

[in]	image	Image to be filtered.
[in]	size	Either Filter::FixedFilterSize::Kernel3x3 or Filter::FixedFilterSize::Kernel5x5.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

◆ HighPass()

std::unique_ptr< Image > HighPass	(	const Image &	image,
		Filter::FixedFilterSize	size
	)

inline

This function applies a square high pass filter to an image.

Parameters

[in]	image	Image to be filtered.
[in]	size	Either Filter::FixedFilterSize::Kernel3x3 or Filter::FixedFilterSize::Kernel5x5.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

◆ Laplace()

std::unique_ptr< Image > Laplace	(	const Image &	image,
		Filter::FixedFilterSize	size
	)

inline

This function applies a square high pass Laplace filter to an image.

Parameters

[in]	image	Image to be filtered.
[in]	size	Either Filter::FixedFilterSize::Kernel3x3 or Filter::FixedFilterSize::Kernel5x5.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

◆ LowPass()

std::unique_ptr< Image > LowPass	(	const Image &	image,
		Filter::FixedFilterSize	size
	)

inline

This function applies a square low pass filter to an image.

Parameters

[in]	image	Image to be filtered.
[in]	size	Either Filter::FixedFilterSize::Kernel3x3 or Filter::FixedFilterSize::Kernel5x5.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

◆ Prewitt()

std::unique_ptr< Image > Prewitt	(	const Image &	image,
		Filter::FilterOrientation	orientation
	)

inline

Applies a Prewitt edge filter to the input image.

Parameters

[in]	image	Image to filter.
[in]	orientation	Orientation of the filter.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

Note that the Prewitt filter zeros out negative edges - if you want to use a filter that preserves the negative edges, please use Sobel() or Scharr() instead.

◆ Roberts()

std::unique_ptr< Image > Roberts	(	const Image &	image,
		Filter::RobertsDirection	direction
	)

inline

Apply a Roberts edge detector to the input image.

Parameters

[in]	image	Image to be filtered.
[in]	direction	Filter direction.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

Result values of the Roberts filter that are less than zero will be zeroed out.

◆ Scharr()

std::unique_ptr< Image > Scharr	(	const Image &	image,
		Filter::FilterOrientation	orientation
	)

inline

Applies a Scharr edge filter to the input image.

Parameters

[in]	image	Image to filter.
[in]	orientation	Orientation of the filter.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

The Scharr filter's output, in case of an 8 bit monochrome input image, will be scaled to the range 0...255, with 128 corresponding to a filter result of zero.

◆ Sharpen()

std::unique_ptr< Image > Sharpen ( const Image & image )

inline

This function applies a Filter::FixedFilterSize::Kernel3x3 sharpen filter to an image.

Parameters

[in] image Image to be filtered.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

◆ Sobel()

std::unique_ptr< Image > Sobel	(	const Image &	image,
		Filter::FilterOrientation	orientation,
		Filter::FixedFilterSize	maskSize
	)

inline

Applies a Sobel edge filter to the input image.

Parameters

[in]	image	Image to filter.
[in]	orientation	Orientation of the filter.
[in]	maskSize	Mask size (Filter::FixedFilterSize::Kernel3x3 or Filter::FixedFilterSize::Kernel5x5).

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

The Sobel filter's output, in case of an 8 bit monochrome input image, will be scaled to the range 0...255, with 128 corresponding to a filter result of zero.

◆ Sobel2nd()

std::unique_ptr< Image > Sobel2nd	(	const Image &	image,
		Filter::FilterOrientation	orientation,
		Filter::FixedFilterSize	maskSize
	)

inline

Applies a 2nd order Sobel edge filter to the input image.

Parameters

[in]	image	Image to filter.
[in]	orientation	Orientation of the filter.
[in]	maskSize	Mask size (Filter::FixedFilterSize::Kernel3x3 or Filter::FixedFilterSize::Kernel5x5).

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

The Sobel filter's output, in case of an 8 bit monochrome input image, will be scaled to the range 0...255, with 128 corresponding to a filter result of zero.

◆ Sobel2ndCross()

std::unique_ptr< Image > Sobel2ndCross	(	const Image &	image,
		Filter::FixedFilterSize	maskSize
	)

inline

Applies a 2nd order Sobel cross edge filter to the input image.

Parameters

[in]	image	Image to filter.
[in]	maskSize	Mask size (Filter::FixedFilterSize::Kernel3x3 or Filter::FixedFilterSize::Kernel5x5).

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

The Sobel filter's output, in case of an 8 bit monochrome input image, will be scaled to the range 0...255, with 128 corresponding to a filter result of zero.

◆ Wiener() [1/2]

std::unique_ptr< Image > Wiener	(	const Image &	image,
		Size2D< int >	maskSize,
		double	noiseThreshold = `0.0`
	)

inline

This function performs adaptive filtering of an image degraded by constant power additive noise.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.
[in]	noiseThreshold	Noise suppression threshold. Valid input ranges from 0 to 1, with 0 causing the function to determine the threshold automatically.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

For each pixel of the input image, the function determines the local image mean and variance in the rectangular neighborhood (mask) defined by maskSize and maskOffset. The deviation from the local average is then diminished according to the local variance and the noise threshold parameters. The noise threshold parameter may be zero, in which case the function tries to determine itself what local noise threshold to apply. This normally yields the best results. Mask offset is automatically set to the center of the mask rectangle.

◆ Wiener() [2/2]

std::unique_ptr< Image > Wiener	(	const Image &	image,
		Size2D< int >	maskSize,
		Point2D< int >	maskOffset,
		double	noiseThreshold = `0.0`
	)

inline

This function performs adaptive filtering of an image degraded by constant power additive noise.

Parameters

[in]	image	Image to be filtered.
[in]	maskSize	Filter mask to be used.
[in]	maskOffset	Mask center pixel location.
[in]	noiseThreshold	Noise suppression threshold. Valid input ranges from 0 to 1, with 0 causing the function to determine the threshold automatically.

Returns: The filtered image.

Exceptions

Any	exception derived from std::exception including CvbException.

For each pixel of the input image, the function determines the local image mean and variance in the rectangular neighborhood (mask) defined by maskSize and maskOffset. The deviation from the local average is then diminished according to the local variance and the noise threshold parameters. The noise threshold parameter may be zero, in which case the function tries to determine itself what local noise threshold to apply. This normally yields the best results.

Enumerations

Functions

Detailed Description

Enumeration Type Documentation

◆ EdgeFilter

◆ FilterOrientation

◆ FixedFilterSize

◆ RobertsDirection

Function Documentation

◆ BoxMax() [1/2]

◆ BoxMax() [2/2]

◆ BoxMean() [1/2]

◆ BoxMean() [2/2]

◆ BoxMedian() [1/2]

◆ BoxMedian() [2/2]

◆ BoxMin() [1/2]

◆ BoxMin() [2/2]

◆ Canny()

◆ ColorMedian()

◆ Gauss()

◆ HighPass()

◆ Laplace()

◆ LowPass()

◆ Prewitt()

◆ Roberts()

◆ Scharr()

◆ Sharpen()

◆ Sobel()

◆ Sobel2nd()

◆ Sobel2ndCross()

◆ Wiener() [1/2]

◆ Wiener() [2/2]