Isis::Stretch Class Reference
[Utility]

#include <Stretch.h>

Public Member Functions
	Stretch ()
	Constructs a Stretch object with default mapping of special pixel values to themselves.
	~Stretch ()
	Destroys the Stretch object.
void	AddPair (const double input, const double output)
	Adds a stretch pair to the list of pairs.
void	SetNull (const double value)
	Sets the mapping for NULL pixels.
void	SetLis (const double value)
	Sets the mapping for LIS pixels.
void	SetLrs (const double value)
	Sets the mapping for LRS pixels.
void	SetHis (const double value)
	Sets the mapping for HIS pixels.
void	SetHrs (const double value)
	Sets the mapping for HRS pixels.
void	SetMinimum (const double value)
void	SetMaximum (const double value)
void	Load (Pvl &pvl, std::string &grpName)
	Loads the stretch pairs from the pvl file into the Stretch object.
void	Save (Pvl &pvl, std::string &grpName)
void	Load (std::string &file, std::string &grpName)
	Loads the stretch pairs from the pvl file into the Stretch object.
void	Save (std::string &file, std::string &grpName)
	Saves the stretch pairs in the Stretch object into the given pvl file.
double	Map (const double value) const
	Maps an input value to an output value based on the stretch pairs and/or special pixel mappings.
void	Parse (const std::string &pairs)
	Parses a string of the form "i1:o1 i2:o2...iN:oN" where each i:o represents an input:output pair.
void	Parse (const std::string &pairs, const Isis::Histogram *hist)
	Parses a string of the form "i1:o1 i2:o2...iN:oN" where each i:o represents an input:output pair where the input is a percentage.
std::string	Text () const
	Converts stretch pair to a string.
int	Pairs () const
	Returns the number of stretch pairs.
double	Input (const int index) const
	Returns the value of the input side of the stretch pair at the specified index.
double	Output (const int index) const
	Returns the value of the output side of the stretch pair at the specified index.
void	ClearPairs ()
	Clears the stretch pairs.
void	CopyPairs (const Stretch &other)
	Copies the stretch pairs from another Stretch object, but maintains special pixel values.

Detailed Description

Pixel value mapper.

This class is used to stretch or remap pixel values. For example, it can be used to apply contrast stretches, color code stretches, or remap from a double range to 8-bit (0 to 255). The methodology used is straightforward. The program must set up a list of stretch pairs, input-to-output mappings, using the AddPair method. For example, (0,0) and (1,255) are two pairs which would cause an input of 0 to be mapped to 0, 0.5 would be mapped to 127.5 and 1 would be mapped to 255. More than two pairs can be used which generates piece-wise linear mappings. Special pixels are mapped to themselves unless overridden with methods such as SetNull. Input values outside the minimum and maximum input pair values are mapped to LRS and HRS respectively.

If you would like to see Stretch being used in implementation, see stretch.cpp

Author:: 2002-05-15 Jeff Anderson

Constructor & Destructor Documentation

Isis::Stretch::Stretch ( )

Constructs a Stretch object with default mapping of special pixel values to themselves.

References Isis::HIGH_INSTR_SAT8, Isis::HIGH_REPR_SAT8, Isis::LOW_INSTR_SAT8, Isis::LOW_REPR_SAT8, and Isis::NULL8.

Isis::Stretch::~Stretch ( ) [inline]

Destroys the Stretch object.

Member Function Documentation

void Isis::Stretch::AddPair	(	const double	input,
		const double	output
	)

Adds a stretch pair to the list of pairs.

Note that all input pairs must be in ascending order.

Parameters:

	input	Input value to map
	output	Output value when the input is mapped

Exceptions:

Isis::iException::Programmer

- input pairs must be in ascending order

References _FILEINFO_, Isis::iException::Message(), and Isis::iException::Programmer.

Referenced by Isis::GaussianStretch::GaussianStretch(), Load(), Parse(), Isis::VisualDisplay::setPixelData(), Isis::LinearStretchType::setStretch(), Isis::StretchTool::stretchBand(), and Isis::StretchTool::stretchBuffer().

void Isis::Stretch::ClearPairs ( ) [inline]

Clears the stretch pairs.

Referenced by Isis::GaussianStretch::GaussianStretch(), Isis::VisualDisplay::setPixelData(), and Isis::StretchTool::stretchBand().

void Isis::Stretch::CopyPairs ( const Stretch & other )

Copies the stretch pairs from another Stretch object, but maintains special pixel values.

Parameters:

other

- The Stretch to copy pairs from

Referenced by Isis::IndependentCubeViewport::restretch(), Isis::SawtoothStretchType::setStretch(), Isis::ManualStretchType::setStretch(), Isis::LinearStretchType::setStretch(), and Isis::StretchTool::stretchRequested().

double Isis::Stretch::Input ( const int index ) const

Returns the value of the input side of the stretch pair at the specified index.

If the index number is out of bounds, then the method returns -1

Parameters:

index

The index number to retrieve the input stretch pair value from

Returns:: double The input side of the stretch pair at the specified index

Referenced by Save(), Isis::SawtoothStretchType::setStretch(), Isis::LinearStretchType::setStretch(), Isis::HistogramWidget::setStretch(), and Isis::StretchType::updateTable().

void Isis::Stretch::Load	(	std::string &	file,
		std::string &	grpName
	)

Loads the stretch pairs from the pvl file into the Stretch object.

The file should look similar to this:

 Group = Pairs
   Input = (0,100,255)
   Output = (255,100,0)
 EndGroup

Parameters:

	file	- The input file containing the stretch pairs
	grpName	- The group name to get the input and output keywords from

References Load(), and pvl().

void Isis::Stretch::Load	(	Isis::Pvl &	pvl,
		std::string &	grpName
	)

Loads the stretch pairs from the pvl file into the Stretch object.

The pvl should look similar to this:

 Group = Pairs
   Input = (0,100,255)
   Output = (255,100,0)
 EndGroup

Parameters:

	pvl	- The pvl containing the stretch pairs
	grpName	- The group name to get the input and output keywords from

References _FILEINFO_, AddPair(), Isis::PvlObject::FindGroup(), Isis::PvlContainer::FindKeyword(), Isis::iException::Message(), Isis::PvlKeyword::Size(), Isis::PvlObject::Traverse, and Isis::iException::User.

Referenced by Load().

double Isis::Stretch::Map ( const double value ) const

Maps an input value to an output value based on the stretch pairs and/or special pixel mappings.

Parameters:

value

Value to map

Returns:: double The mapped output value is returned by this method

References Isis::IsHisPixel(), Isis::IsHrsPixel(), Isis::IsLisPixel(), Isis::IsNullPixel(), and Isis::IsValidPixel().

Referenced by Isis::GaussianStretch::Map(), and Isis::VisualDisplay::paintPixmap().

double Isis::Stretch::Output ( const int index ) const

Returns the value of the output side of the stretch pair at the specified index.

If the index number is out of bounds, then the method returns -1.

Parameters:

index

The index number to retieve the output stretch pair value from

Returns:: double The output side of the stretch pair at the specified index

Referenced by Save(), Isis::SawtoothStretchType::setStretch(), Isis::HistogramWidget::setStretch(), and Isis::StretchType::updateTable().

int Isis::Stretch::Pairs ( ) const [inline]

Returns the number of stretch pairs.

Referenced by Save(), Isis::SawtoothStretchType::setStretch(), Isis::LinearStretchType::setStretch(), Isis::HistogramWidget::setStretch(), Isis::StretchTool::stretchBuffer(), and Isis::StretchType::updateTable().

void Isis::Stretch::Parse	(	const std::string &	pairs,
		const Isis::Histogram *	hist
	)

Parses a string of the form "i1:o1 i2:o2...iN:oN" where each i:o represents an input:output pair where the input is a percentage.

Using the Histogram an appropriate dn value will be calculated for each input percentage. Therefore, the user can enter a string in this form and this method will parse the string and load the stretch pairs into the object via AddPairs.

Parameters:

pairs

A string containing stretch pairs for example "0:0 50:0 100:255"

Exceptions:

Isis::iException::User

- invalid stretch pair

References _FILEINFO_, AddPair(), Isis::iException::Message(), Isis::Histogram::Percent(), Isis::iString::TrimHead(), and Isis::iException::User.

void Isis::Stretch::Parse ( const std::string & pairs )

Parses a string of the form "i1:o1 i2:o2...iN:oN" where each i:o represents an input:output pair.

Therefore, the user can enter a string in this form and this method will parse the string and load the stretch pairs into the object via AddPairs.

Parameters:

pairs

A string containing stretch pairs for example "0:0 50:0 100:255 255:255"

Exceptions:

Isis::iException::User

- invalid stretch pair

References _FILEINFO_, AddPair(), Isis::iException::Message(), Isis::iString::TrimHead(), and Isis::iException::User.

Referenced by Isis::CubeViewport::stretchBlue(), Isis::CubeViewport::stretchGray(), Isis::CubeViewport::stretchGreen(), and Isis::CubeViewport::stretchRed().

void Isis::Stretch::Save	(	std::string &	file,
		std::string &	grpName
	)

Saves the stretch pairs in the Stretch object into the given pvl file.

Parameters:

	file	- The file that the stretch pairs will be written to
	grpName	- The name of the group to create and put the stretch pairs into. The group will contain two keywords, Input, and Output.

References Save(), and Isis::Pvl::Write().