lti::csPresegmentation Class Reference

The csPresegmentation functor (states for color space presegmentation) tries to detect which pixels belong to the background and which not. More...

#include <ltiCsPresegmentation.h>

Inheritance diagram for lti::csPresegmentation:

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List of all members.

Classes
class	parameters
	the parameters for the class csPresegmentation More...
Public Member Functions
	csPresegmentation ()
	csPresegmentation (const csPresegmentation &other)
virtual	~csPresegmentation ()
virtual const char *	getTypeName () const
bool	apply (const image &src, channel8 &mask)
csPresegmentation &	copy (const csPresegmentation &other)
csPresegmentation &	operator= (const csPresegmentation &other)
virtual functor *	clone () const
const parameters &	getParameters () const
Protected Member Functions
bool	validBackground (const rgbPixel &p, const trgbPixel< float > &mean, const trgbPixel< float > &var, const float &tolerance) const
Protected Attributes
palette	lastPalette

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Detailed Description

The csPresegmentation functor (states for color space presegmentation) tries to detect which pixels belong to the background and which not.

For its task there are some assumtions/requirements:

• The background must be homogeneous, i.e. no textures are allowed. The best results are obtained with a black background, but this is not necessary.
• The number of "perceivable" colors in the image is less than the number of quantization colors given in the parameters.
• There is a high probability that the border of the image contains only background pixels.

These conditions are not met in many applications, for which other segmentation approaches have to be found.

The algorithm works as follows:

First, a color quantization using k-Means is done. This produces usually a "noisy" index mask and a palette. A median filter or a k-Nearest-Neighbor Filter smooths this mask. Assuming that the border of the image contains mostly background pixels, some simple statistics are done, to decide which palette entries belong to the background. Pixels belonging to other palette entries are taken as the object pixels.

See the lti::csPresegmentation::parameters for more information.

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Constructor & Destructor Documentation

lti::csPresegmentation::csPresegmentation

(

)

default constructor

lti::csPresegmentation::csPresegmentation

(

const csPresegmentation &

other

)

copy constructor

Parameters:

other

the object to be copied

virtual lti::csPresegmentation::~csPresegmentation

(

)

[virtual]

destructor

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Member Function Documentation

bool lti::csPresegmentation::apply	(	const image &	src,
		channel8 &	mask
	)

apply the presegmentation algorithm to the given image and return a mask where the background pixels will be mark with the value zero and the non-background pixels with a non-zero value.

Note that some information of this segmentation is "stored" in the internal state, which affects the next segmentation steps. (see lti::csPresegmentation::parameters::useAlwaysNewPalette)

Parameters:

	src	image with the source data.
	mask	the mask with the found objects.

Returns:

true if apply successful or false otherwise.

virtual functor* lti::csPresegmentation::clone

(

)

const [virtual]

returns a pointer to a clone of this functor.

Reimplemented from lti::segmentation.

csPresegmentation& lti::csPresegmentation::copy

(

const csPresegmentation &

other

)

copy data of "other" functor.

Parameters:

other

the functor to be copied

Returns:

a reference to this functor object

Reimplemented from lti::segmentation.

const parameters& lti::csPresegmentation::getParameters

(

)

const

returns used parameters

Reimplemented from lti::functor.

virtual const char* lti::csPresegmentation::getTypeName

(

)

const [virtual]

returns the name of this type ("csPresegmentation")

Reimplemented from lti::segmentation.

csPresegmentation& lti::csPresegmentation::operator=

(

const csPresegmentation &

other

)

alias for copy member

Parameters:

other

the functor to be copied

Returns:

a reference to this functor object

Reimplemented from lti::functor.

bool lti::csPresegmentation::validBackground	(	const rgbPixel &	p,
		const trgbPixel< float > &	mean,
		const trgbPixel< float > &	var,
		const float &	tolerance
	)			const [inline, protected]

valid background returns true if the given pixel lies between the mean value and the given variance.

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Member Data Documentation

palette lti::csPresegmentation::lastPalette [protected]

last used palette

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The documentation for this class was generated from the following file:

• ltiCsPresegmentation.h