Useful functions for working with images

Classes
class	mx::improc::sourceFinder< _realT >
	Find stars in an image by SNR thresholding. More...

Functions
template<typename realT >
int	mx::improc::circleOuterpix (realT &x0, realT &y0, realT &avgr0, realT &avgx, realT &avgy, realT &avgr, eigenImage< realT > &circ, const eigenImage< realT > &masked)
	Find the center and the outermost pixels of a circular mask, giving an estimate of the radius. More...

template<typename realT >
int	mx::improc::reflectImageCoords (int &x1, int &y1, int x0, int y0, realT xc, realT yc)
	Reflect pixel coordinates across the given center pixel. More...

template<class imageT , typename valueT >
void	mx::improc::zeroNaNs (imageT &im, valueT val)
	Zero any NaNs in an image. More...

template<class imageT >
void	mx::improc::zeroNaNs (imageT &im)
	Zero any NaNs in an image. More...

template<class cubeT >
void	mx::improc::zeroNaNCube (cubeT &imc)
	Zero any NaNs in an image cube. More...

template<class imageT >
imageT::Scalar	mx::improc::imageMean (imageT &im)
	Calculate the mean value of an image. More...

template<class imageT >
imageT::Scalar	mx::improc::imageVariance (imageT &im, typename imageT::Scalar mean)
	Calculate the variance of an image w.r.t. a given value. More...

template<typename imageT >
int	mx::improc::imageCenterOfLight (typename imageT::Scalar &x, typename imageT::Scalar &y, const imageT &im)
	Calculate the center of light of an image. More...

template<typename floatT , typename imageT , typename magImageT , typename transformT >
int	mx::improc::imageMaxInterp (floatT &x, floatT &y, floatT &scale_x, floatT &scale_y, magImageT &magIm, const imageT &im, transformT trans)
	Find the maximum in an image at sub-pixel resolution by interpolation. More...

template<typename floatT , typename imageT , typename magImageT >
int	mx::improc::imageMaxInterp (floatT &x, floatT &y, floatT &scale_x, floatT &scale_y, magImageT &magIm, const imageT &im)
	Find the maximum in an image at sub-pixel resolution by cubic convolution interpolation. More...

template<typename imageT , typename imageT1 , typename imageT2 , typename imageT3 , typename imageT4 >
void	mx::improc::combine2ImagesMasked (imageT &combo, const imageT1 &im1, const imageT2 &mask1, const imageT3 &im2, const imageT4 &mask2)
	Combine two images, each with their own mask defining good pixels. More...

void *	mx::improc::imcpy (void dest, void src, size_t width, size_t height, size_t szof)
	Copy one image to another, with no transformation. More...

void *	mx::improc::imcpy_flipUD (void dest, void src, size_t width, size_t height, size_t szof)
	Copy one image to another, flipping up-down. More...

void *	mx::improc::imcpy_flipLR (void dest, void src, size_t width, size_t height, size_t szof)
	Copy one image to another, flipping left-right. More...

void *	mx::improc::imcpy_flipUDLR (void dest, void src, size_t width, size_t height, size_t szof)
	Copy one image to another, flipping up-down and left-right. More...

Function Documentation

◆ circleOuterpix()

template<typename realT >

int mx::improc::circleOuterpix	(	realT &	x0,
		realT &	y0,
		realT &	avgr0,
		realT &	avgx,
		realT &	avgy,
		realT &	avgr,
		eigenImage< realT > &	circ,
		const eigenImage< realT > &	masked
	)

Find the center and the outermost pixels of a circular mask, giving an estimate of the radius.

Takes a 1/0 mask of a filled circle or annulus, and calculates the center coordinate by center-of-light, then finds the outermost 1 pixel in each row and column. Calculates the average radius of these pixels w.r.t. to the c.o.l. coords, as well as w.r.t. the average coords of the outer pixels themselves.

Also produces an image containing the outer pixels.

Returns: 0 on success

Template Parameters

realT the real floating-point type for calculations

Parameters

y0	< [out] x coord of center of the mask by center-of-light
avgr0	< [out] y coord of center of the mask by center-of-light
avgx	< [out] average radius of edge pixels w.r.t. center-of-light
avgy	< [out] x coord of center of the mask by average edge pixel
avgr	< [out] y coord of center of the mask by average edge pixel
circ	< [out] average radius of edge pixels w.r.t. to average edge pixel
masked	< [out] image showing the edge pixels with value 1, all other pixels 0. Resized. < [in] an image with a (roughly) circular mask of 1s

Definition at line 56 of file circleOuterpix.hpp.

References mx::improc::imageCenterOfLight(), and mx::math::pi().

◆ combine2ImagesMasked()

template<typename imageT , typename imageT1 , typename imageT2 , typename imageT3 , typename imageT4 >

void mx::improc::combine2ImagesMasked	(	imageT &	combo,
		const imageT1 &	im1,
		const imageT2 &	mask1,
		const imageT3 &	im2,
		const imageT4 &	mask2
	)

Combine two images, each with their own mask defining good pixels.

The combined image is made up of the pixels in im1 where mask1 is 1, and the pixels of im2 where mask2 is 1. If a pixel in both mask1 and mask2 has a value of 1, that pixel in the combo is the average of im1 and im2. All other pixels are set to 0 in the combined image.

Separate template types are used for each argument to allow references, etc.

Template Parameters

imageT	the eigen-like array type of the combined image
imageT1	the eigen-like array type of image 1
imageT2	the eigen-like array type of mask 1
imageT3	the eigen-like array type of image 2
imageT4	the eigen-like array type of mask 2

Parameters

[out]	combo	the combined image. will be resized.
[in]	im1	the first image
[in]	mask1	the mask for the first image
[in]	im2	the second image
[in]	mask2	the mask for the second image

Definition at line 267 of file imageUtils.hpp.

References mx::astro::constants::c().

◆ imageCenterOfLight()

template<typename imageT >

int mx::improc::imageCenterOfLight	(	typename imageT::Scalar &	x,
		typename imageT::Scalar &	y,
		const imageT &	im
	)

Calculate the center of light of an image.

Note that the sum of the image should be > 0.

Parameters

[out]	x	the x coordinate of the center of light [pixels]
[out]	y	the y coordinate of hte center of light [pixels]
[in]	im	the image to centroid

Definition at line 163 of file imageUtils.hpp.

Referenced by mx::improc::circleOuterpix(), and SCENARIO().

◆ imageMaxInterp() [1/2]

template<typename floatT , typename imageT , typename magImageT >

int mx::improc::imageMaxInterp	(	floatT &	x,
		floatT &	y,
		floatT &	scale_x,
		floatT &	scale_y,
		magImageT &	magIm,
		const imageT &	im
	)

Find the maximum in an image at sub-pixel resolution by cubic convolution interpolation.

Uses imageMagnify() to expand the image to the desired scale. Because of the scaling used in imageMagnify, the desired scale may not be exact. As a result the actual scale is returned in scale_x and scale_y.

Parameters

[out]	x	the x-position of the maximum, in pixels of the input image
[out]	y	the y-position of the maximum, in pixels of the input image
	scale_x	[in.out] the desired scale or resolution, in pixels < 1, in the x direction. On output contains the actual scale calculated.
	scale_y	[in.out] the desired scale or resolution, in pixels < 1, in the y direction. On output contains the actual scale calculated.
[in]	magIm	the magnified image. This is used as working memory, will be resized.
[in]	im	the image to find the maximum of

Definition at line 239 of file imageUtils.hpp.

◆ imageMaxInterp() [2/2]

template<typename floatT , typename imageT , typename magImageT , typename transformT >

int mx::improc::imageMaxInterp	(	floatT &	x,
		floatT &	y,
		floatT &	scale_x,
		floatT &	scale_y,
		magImageT &	magIm,
		const imageT &	im,
		transformT	trans
	)

Find the maximum in an image at sub-pixel resolution by interpolation.

Uses imageMagnify() to expand the image to the desired scale. Because of the scaling used in imageMagnify, the desired scale may not be exact. As a result the actual scale is returned in scale_x and scale_y.

Parameters

[out]	x	the x-position of the maximum, in pixels of the input image
[out]	y	the y-position of the maximum, in pixels of the input image
	scale_x	[in.out] the desired scale or resolution, in pixels < 1, in the x direction. On output contains the actual scale calculated.
	scale_y	[in.out] the desired scale or resolution, in pixels < 1, in the y direction. On output contains the actual scale calculated.
[in]	magIm	the magnified image. This is used as working memory, will be resized.
[in]	im	the image to find the maximum of
[in]	trans	the transform to use for interpolation

Definition at line 202 of file imageUtils.hpp.

References mx::improc::imageMagnify().

◆ imageMean()

template<class imageT >

imageT::Scalar mx::improc::imageMean ( imageT & im )

Calculate the mean value of an image.

Returns: the mean of the input image

Parameters

[in] im the image of which to calculate the mean

Definition at line 116 of file imageUtils.hpp.

References mx::astro::constants::c().

◆ imageVariance()

template<class imageT >

imageT::Scalar mx::improc::imageVariance	(	imageT &	im,
		typename imageT::Scalar	mean
	)

Calculate the variance of an image w.r.t. a given value.

Returns: the variance of the input image

Parameters

[in]	im	the image of which to calculate the variance
[in]	mean	the value to calculate the variance with respect to

Definition at line 139 of file imageUtils.hpp.

References mx::astro::constants::c().

Referenced by mx::improc::imageXCorrDiscrete< _ccImT >::operator()(), mx::improc::imageXCorrFFT< _ccImT >::operator()(), mx::improc::imageXCorrDiscrete< _ccImT >::refIm(), and mx::improc::imageXCorrFFT< _ccImT >::refIm().

◆ imcpy()

void * mx::improc::imcpy	(	void *	dest,
		void *	src,
		size_t	width,
		size_t	height,
		size_t	szof
	)

Copy one image to another, with no transformation.

This is merely memcpy

Returns: dest

Parameters

[out]	dest	the address of the first pixel in the destination image
[in]	src	the address of the first pixel in the source image
[in]	width	the width in pixels of size szof
[in]	height	the height in pixels of size szof
[in]	szof	the size in bytes of a one pixel

Definition at line 35 of file imageUtils.cpp.

◆ imcpy_flipLR()

void * mx::improc::imcpy_flipLR	(	void *	dest,
		void *	src,
		size_t	width,
		size_t	height,
		size_t	szof
	)

Copy one image to another, flipping left-right.

Returns: dest

Parameters

[out]	dest	the address of the first pixel in the destination image
[in]	src	the address of the first pixel in the source image
[in]	width	the width in pixels of size szof
[in]	height	the height in pixels of size szof
[in]	szof	the size in bytes of a one pixel

Definition at line 60 of file imageUtils.cpp.

◆ imcpy_flipUD()

void * mx::improc::imcpy_flipUD	(	void *	dest,
		void *	src,
		size_t	width,
		size_t	height,
		size_t	szof
	)

Copy one image to another, flipping up-down.

This is a reversed row-by-row memcpy

Returns: dest

Parameters

[out]	dest	the address of the first pixel in the destination image
[in]	src	the address of the first pixel in the source image
[in]	width	the width in pixels of size szof
[in]	height	the height in pixels of size szof
[in]	szof	the size in bytes of a one pixel

Definition at line 45 of file imageUtils.cpp.

◆ imcpy_flipUDLR()

void * mx::improc::imcpy_flipUDLR	(	void *	dest,
		void *	src,
		size_t	width,
		size_t	height,
		size_t	szof
	)

Copy one image to another, flipping up-down and left-right.

Returns: dest

Parameters

[out]	dest	the address of the first pixel in the destination image
[in]	src	the address of the first pixel in the source image
[in]	width	the width in pixels of size szof
[in]	height	the height in pixels of size szof
[in]	szof	the size in bytes of a one pixel

Definition at line 133 of file imageUtils.cpp.

◆ reflectImageCoords()

template<typename realT >

int mx::improc::reflectImageCoords	(	int &	x1,
		int &	y1,
		int	x0,
		int	y0,
		realT	xc,
		realT	yc
	)

Reflect pixel coordinates across the given center pixel.

Parameters

[out]	x1	the reflected x coordinate
[out]	y1	the reflected y coordinate
[in]	x0	the input x coordinate
[in]	y0	the input y coordinate
[in]	xc	the center pixel x coordinate
[in]	yc	the center pixel y coordinate

Definition at line 46 of file imageUtils.hpp.

Referenced by mx::improc::reflectImageIndices().

◆ zeroNaNCube()

template<class cubeT >

void mx::improc::zeroNaNCube ( cubeT & imc )

Zero any NaNs in an image cube.

Parameters

imc	[in.out] cube which will have any NaN pixels set to zero

Definition at line 93 of file imageUtils.hpp.

References mx::astro::constants::c().

Referenced by mx::improc::HCIobservation< _realT >::readFiles(), mx::improc::HCIobservation< _realT >::readPSFSub(), and mx::improc::HCIobservation< _realT >::readRDIFiles().

◆ zeroNaNs() [1/2]

template<class imageT >

void mx::improc::zeroNaNs ( imageT & im )

Zero any NaNs in an image.

Parameters

im	[in.out] image which will have any NaN pixels set to zero

Definition at line 85 of file imageUtils.hpp.

◆ zeroNaNs() [2/2]

template<class imageT , typename valueT >

void mx::improc::zeroNaNs	(	imageT &	im,
		valueT	val
	)

Zero any NaNs in an image.

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

	im	[in.out] image which will have any NaN pixels set to zero
[in]	val	[optional] The value to set NaN pixels too. Default is 0.

Definition at line 67 of file imageUtils.hpp.

References mx::astro::constants::c().

Classes

Functions

Function Documentation

◆ circleOuterpix()

◆ combine2ImagesMasked()

◆ imageCenterOfLight()

◆ imageMaxInterp() [1/2]

◆ imageMaxInterp() [2/2]

◆ imageMean()

◆ imageVariance()

◆ imcpy()

◆ imcpy_flipLR()

◆ imcpy_flipUD()

◆ imcpy_flipUDLR()

◆ reflectImageCoords()

◆ zeroNaNCube()

◆ zeroNaNs() [1/2]

◆ zeroNaNs() [2/2]