DcmQuantColorHashTable Class Reference

this class implements a hash table for colors. More...

Public Member Functions
	DcmQuantColorHashTable ()
	constructor
	~DcmQuantColorHashTable ()
	destructor
void	add (const DcmQuantPixel &colorP, int value)
	adds a new color to the hash table. More...
int	lookup (const DcmQuantPixel &colorP) const
	looks up the given color in the hash table. More...
unsigned long	addToHashTable (DicomImage &image, unsigned long newmaxval, unsigned long maxcolors)
	adds all pixels of all frames of the given image (which must be a color image) to the hash table. More...
unsigned long	countEntries () const
	counts the number of entries in the hash table More...
unsigned long	createHistogram (DcmQuantHistogramItemPointer *&array)
	converts the contents of this hash table into a histogram array. More...

Private Member Functions
	DcmQuantColorHashTable (const DcmQuantColorHashTable &src)
	private undefined copy constructor
DcmQuantColorHashTable &	operator= (const DcmQuantColorHashTable &src)
	private undefined copy assignment operator
DcmQuantHistogramItemList &	item (const DcmQuantPixel &colorP)
	Retrieves the specified item from the hash table. More...

Private Attributes
table_type	m_Table
	hash array of lists for color/value pairs

Detailed Description

this class implements a hash table for colors.

Each entry of the hash table consists of an RGB color (DcmQuantPixel object) and an integer value (e. g. counter). This class is used during the quantization of a color image.

Member Function Documentation

add()

void DcmQuantColorHashTable::add ( const DcmQuantPixel &  colorP, int  value  )

inline

adds a new color to the hash table.

The color must not yet be present (the caller is responsible for checking this).

Parameters

colorP	color to be added to table
value	integer value (counter) associated to color

addToHashTable()

unsigned long DcmQuantColorHashTable::addToHashTable	(	DicomImage &	image,
		unsigned long	newmaxval,
		unsigned long	maxcolors
	)

adds all pixels of all frames of the given image (which must be a color image) to the hash table.

The counter (integer value associated to each color) counts the occurrence of the color in the image. If more than maxcolors colors are found, the function returns zero.

Parameters

image	image in which colors are to be counted
newmaxval	maximum pixel value to which the contents of the image are scaled down (see documentation of class DcmQuantScaleTable) before counting colors. This is used by the caller to reduce the number of colors in the image if necessary.
maxcolors	maximum number of colors allowed. If more colors are found, the method immediately returns with a return value of zero.

Returns

number of colors found, 0 if too many colors.

countEntries()

unsigned long DcmQuantColorHashTable::countEntries

(

)

const

counts the number of entries in the hash table

Returns

number of entries in hash table

createHistogram()

unsigned long DcmQuantColorHashTable::createHistogram

(

DcmQuantHistogramItemPointer *&

array

)

converts the contents of this hash table into a histogram array.

After a successful call to addToHashTable(), this object contains an image histogram stored in a hash table. This method creates a new array of DcmQuantHistogramItem pointers on the heap and moves the contents of the hash table into this array.

Parameters

array

the hash table array is returned in this parameter

Returns

number of elements in array

item()

DcmQuantHistogramItemList& DcmQuantColorHashTable::item ( const DcmQuantPixel &  colorP )

inlineprivate

Retrieves the specified item from the hash table.

If the item has not been created a new item is created and is returned.

Parameters

colorP

the item in the hash table

Returns

the retrieved, or created object

References DcmQuantPixel::hash().

lookup()

int DcmQuantColorHashTable::lookup ( const DcmQuantPixel &  colorP ) const

inline

looks up the given color in the hash table.

If found, the value associated to the color is returned, -1 otherwise.

Parameters

colorP

color to look up in hash table

Returns

value associated to given color if found, -1 otherwise.

References DcmQuantPixel::hash(), and DcmQuantHistogramItemList::lookup().

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

• dcmimage/include/dcmtk/dcmimage/diqthash.h