cvr::splitImageToYPbPr Class Reference
[Color Analysis]

Computes the YPbPr values from a given RGB color representation (rgbaPixel). More...

#include <cvrSplitImageToYPbPr.h>

Inheritance diagram for cvr::splitImageToYPbPr:

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Collaboration diagram for cvr::splitImageToYPbPr:

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List of all members.

Public Member Functions
	splitImageToYPbPr ()
	splitImageToYPbPr (const splitImageToYPbPr &other)
virtual	~splitImageToYPbPr ()
const std::string &	name () const
splitImageToYPbPr &	copy (const splitImageToYPbPr &other)
splitImageToYPbPr &	operator= (const splitImageToYPbPr &other)
virtual splitImageToYPbPr *	clone () const
virtual splitImageToYPbPr *	newInstance () const
virtual bool	apply (const rgbaPixel &pixel, float &c1, float &c2, float &c3) const
virtual bool	apply (const rgbaPixel &pixel, ubyte &c1, ubyte &c2, ubyte &c3) const
virtual bool	apply (const matrix< rgbaPixel > &img, matrix< float > &c1, matrix< float > &c2, matrix< float > &c3) const
virtual bool	apply (const matrix< rgbaPixel > &img, matrix< ubyte > &c1, matrix< ubyte > &c2, matrix< ubyte > &c3) const

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Detailed Description

Computes the YPbPr values from a given RGB color representation (rgbaPixel).

In the literature, technical and scientific, there is often confusion among the color spaces YUV, YCbCr and YPbPr. Poynton in http://www.poynton.com/notes/colour_and_gamma/ColorFAQ.html explains that YUV is usually never correctly meant, because the color space normally used for component digital video is the YCbCr (ITU-RS601 or CCIR-601). Other devices use the YPbPr, but the "real" YUV is rarely employed.

The CVR-Lib provides all three spaces:

• YCbCr: cvr::splitImageToYCbCr used by IEEE 1394 FireWire cameras
• YPbPr: cvr::splitImageToYPbPr used by some WebCams
• YUV: cvr::splitImageToYUV did they really meant to use this?

This functor splits an RGB images into the color space YPbPr using the conversion equations given by the above mentioned reference:

In the formula above, RGB have been assumed to be in the intervall [0,1]. With it, the Y values will have also be in [0,1], while Pb and Pr will lie between [-0.5 and 0.5]. For the ubyte types an offset of 128 is added to the Pb and Pr values, which are previously scaled by 255.

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Constructor & Destructor Documentation

cvr::splitImageToYPbPr::splitImageToYPbPr

(

)

default constructor

cvr::splitImageToYPbPr::splitImageToYPbPr

(

const splitImageToYPbPr &

other

)

copy constructor

Parameters:

other

the object to be copied

virtual cvr::splitImageToYPbPr::~splitImageToYPbPr

(

)

[virtual]

destructor

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Member Function Documentation

virtual bool cvr::splitImageToYPbPr::apply	(	const matrix< rgbaPixel > &	img,
		matrix< ubyte > &	c1,
		matrix< ubyte > &	c2,
		matrix< ubyte > &	c3
	)			const [virtual]

Split image into 8-bit channels.

N.B.: when casting the transformation result to unsigned shorts (8-bit channel) major rounding errors will occur.

As a result, the merging operation might produce negative values or values > 1, which are truncated subsequently. When accurate Y, U and V values are required, prefer float values.

virtual bool cvr::splitImageToYPbPr::apply	(	const matrix< rgbaPixel > &	img,
		matrix< float > &	c1,
		matrix< float > &	c2,
		matrix< float > &	c3
	)			const [virtual]

split pixel into float channels

virtual bool cvr::splitImageToYPbPr::apply	(	const rgbaPixel &	pixel,
		ubyte &	c1,
		ubyte &	c2,
		ubyte &	c3
	)			const [inline, virtual]

Split pixel into 8-bit values (between 0 and 255).

N.B.: when casting the transformation result to unsigned shorts (8-bit channel) major rounding errors will occur.

As a result, the merging operation might produce negative values or values > 1, which are truncated subsequently.

When accurate Y, U and V values are required, prefer float values

Implements cvr::splitImage.

virtual bool cvr::splitImageToYPbPr::apply	(	const rgbaPixel &	pixel,
		float &	c1,
		float &	c2,
		float &	c3
	)			const [inline, virtual]

split pixel into float values (between 0 and 1)

Implements cvr::splitImage.

virtual splitImageToYPbPr* cvr::splitImageToYPbPr::clone

(

)

const [virtual]

returns a pointer to a clone of this functor.

Implements cvr::splitImage.

splitImageToYPbPr& cvr::splitImageToYPbPr::copy

(

const splitImageToYPbPr &

other

)

copy data of "other" functor.

Parameters:

other

the functor to be copied

Returns:

a reference to this functor object

const std::string& cvr::splitImageToYPbPr::name

(

)

const [virtual]

returns the name of this type ("splitImageToYPbPr")

Implements cvr::functor.

virtual splitImageToYPbPr* cvr::splitImageToYPbPr::newInstance

(

)

const [virtual]

Returns a pointer to a new instance of this functor.

Implements cvr::splitImage.

splitImageToYPbPr& cvr::splitImageToYPbPr::operator=

(

const splitImageToYPbPr &

other

)

alias for copy member

Parameters:

other

the functor to be copied

Returns:

a reference to this functor object

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

• cvrSplitImageToYPbPr.h