Filter With Kernels

Image filtering with a kernel.

The filter function use a kernel that specifies how to filter the image. Filter kernels, usually denoted as type kernelT below, must have the following interface:

struct filterKernel
{
    typedef <eigen-like type> arrayT; // arrayT must have an eigen-like interface
 
    typedef <type> arithT; // the type used for arithmetic, normally `typename arrayT::Scalar`
 
    typedef <verbosity-type> verboseT; // the mxlib verbosity for error reports
 
    //The maxWidth function returns the maximum possible full-width (in either direction) of the kernel
    // Called only once for each call to the filter function
    int maxWidth() const
    {
       //returns the maximum half-width given the configuration
    }
 
    //The setKernel function is called for each pixel.
    void setKernel( arithT x,       // the pixel x-position relative to the image center (not the pixel index)
                    arithT y,       // the pixel y-position relative to the image center (not the pixel index)
                    arrayT & kernel // the array to be resized and populated
                  ) const
    {
       //This must resize and populate the passed in kernel array each time
       //so that it is re-entrant.
 
       //Note: On output kernel array should be normalized so that sum() = 1.0
 
       //Note: the width and height of the kernel array should always be odd
    }
};

Additionally kernelT must be copyable.

/ / Symetric Gaussian smoothing kernel /**

Classes
struct	mx::improc::azBoxKernel< _arrayT, _kernW, _verboseT >
	Azimuthally variable boxcar kernel. More...

Functions
template<typename imageOutT , typename imageInT , typename kernelT >
error_t	mx::improc::filterImage (imageOutT &fim, imageInT im, const kernelT &kernel, int maxr=0)
	Filter an image with a mean kernel.
template<typename imageOutT , typename imageInT , typename kernelT >
void	mx::improc::medianFilterImage (imageOutT &fim, imageInT im, const kernelT &kernel, int maxr=0, int maxrproc=1)
	Filter an image with a median kernel.

Function Documentation

filterImage()

template<typename imageOutT , typename imageInT , typename kernelT >

error_t mx::improc::filterImage	(	imageOutT &	fim,
		imageInT	im,
		const kernelT &	kernel,
		int	maxr = 0
	)

Filter an image with a mean kernel.

Applies the kernel to each pixel in the image and sums, storing the filtered result in the output image.

Template Parameters

imageOutT	the type of the output image (must have an Eigen-like interface)
imageInT	the type of the input image (must have an Eigen-like interface)
kernelT	is the kernel type (see above for requirements)

Parameters

[out]	fim	Contains the filtered image, will be resized
[in]	im	the image to be filtered
[in]	kernel	a fully configured kernel object
[in]	maxr	[opt] the maximum radius from the image center to apply the kernel. pixels outside this radius are set to 0.

Definition at line 395 of file imageFilters.hpp.

References mx::noerror.

Referenced by mx::AO::applyPupil2Basis(), and mx::improc::imCenterCircleSym< realT >::center().

medianFilterImage()

template<typename imageOutT , typename imageInT , typename kernelT >

void mx::improc::medianFilterImage	(	imageOutT &	fim,
		imageInT	im,
		const kernelT &	kernel,
		int	maxr = 0,
		int	maxrproc = 1
	)

Filter an image with a median kernel.

Calculates the median of all pixels corresponding to non-zero pixels in the kernel, storing the filtered result in the output image.

Template Parameters

imageOutT	the type of the output image (must have an Eigen-like interface)
imageInT	the type of the input image (must have an Eigen-like interface)
kernelT	is the kernel type (see above for requirements)

Parameters

[out]	fim	Contains the filtered image, will be resized
[in]	im	the image to be filtered
[in]	kernel	a fully configured kernel object
[in]	maxr	[opt] the maximum radius from the image center to apply the kernel. Psixels outside this radius are set to 0.

Definition at line 540 of file imageFilters.hpp.

References mx::math::vectorMedianInPlace().