cvrSplitImageToYIQ.h

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/*
 * Copyright (C) 1999
 * Lehrstuhl fuer Technische Informatik, RWTH-Aachen, Germany
 *
 *
 * This file is part of the Computer Vision and Robotics Library (CVR-Lib)
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/**
 * \file   cvrSplitImageToYIQ.h
 *         Split color image to YIQ
 * \author Pablo Alvarado
 * \author Stefan Syberichs
 * \author Thomas Rusert
 * \date   19.04.1999
 *
 * $Id: cvrSplitImageToYIQ.h,v 1.1 2007/04/05 22:56:36 alvarado Exp $
 */


#ifndef _CVR_SPLIT_IMAGE_TO_YIQ_H_
#define _CVR_SPLIT_IMAGE_TO_YIQ_H_

#include "cvrSplitImage.h"

namespace cvr {

  /**
   * Split image in its Luminance Inphase Quadrature channels.
   *
   * The following is an excerpt of
   * <a href="http://www.cs.rit.edu/~ncs/color/t_convert.html">this page</a>
   *
   * The YIQ system is the color primary system adopted by National
   * Television System Committee (NTSC) for color TV broadcasting. The
   * YIQ color solid is made by a linear transformation of the RGB
   * cube. Its purpose is to exploit certain characteristics of the
   * human eye to maximize the utilization of a fixed bandwidth. The
   * human visual system is more sensitive to changes in luminance
   * than to changes in hue or saturation, and thus a wider bandwidth
   * should be dedicated to luminance than to color information. Y is
   * similar to perceived luminance, I and Q carry color information
   * and some luminance information. The Y signal usually has 4.2 MHz
   * bandwidth in a 525 line system. Originally, the I and Q had
   * different bandwidths (1.5 and 0.6 MHz), but now they commonly
   * have the same bandwidth of 1 MHz.
   *
   * Here is the RGB -> YIQ conversion:
   *
   * \code
   * [ Y ]     [ 0.299   0.587   0.114 ] [ R ]
   * [ I ]  =  [ 0.596  -0.275  -0.321 ] [ G ]
   * [ Q ]     [ 0.212  -0.523   0.311 ] [ B ]
   * \endcode
   * Here is the YIQ -> RGB conversion:
   * \code
   * [ R ]     [ 1   0.956   0.621 ] [ Y ]
   * [ G ]  =  [ 1  -0.272  -0.647 ] [ I ]
   * [ B ]     [ 1  -1.105   1.702 ] [ Q ]
   * \endcode
   *
   * This color space is not used anymore.  Modern systems use the YUV, YCbCr
   * or YPbPr spaces instead.
   *
   * @see cvr::splitImageToYUV, cvr::splitImageToYCbCr, cvr::splitImageToYPbPr
   *
   * @ingroup gColor
   */
  class splitImageToYIQ : public splitImage {
  public:

    /**
     * returns the name of this type
     */
    virtual const std::string& name() const;

    /**
     * returns a pointer to a clone of the functor
     */
    virtual splitImageToYIQ* clone() const;

    /**
     * Returns a pointer to a new instance of this functor.
     */
    virtual splitImageToYIQ* newInstance() const;

    /**
     * split the image in YIQ.
     * YIQ splitting produces unnormalized channels !
     * @param img the image to be splitted
     * @param Y the perceived luminance
     * @param I color information and some luminance
     * @param Q color information and some luminance
     */
    virtual bool apply(const matrix<rgbaPixel>& img,
                       matrix<float>& Y,
                       matrix<float>& I,
                       matrix<float>& Q) const;

    /**
     * split the image in YIQ.
     * YIQ splitting produces unnormalized channels !
     * @param img the image to be splitted
     * @param Y the perceived luminance
     * @param I color information and some luminance
     * @param Q color information and some luminance
     */
    virtual bool apply(const matrix<rgbaPixel>& img,
                       matrix<ubyte>& Y,
                       matrix<ubyte>& I,
                       matrix<ubyte>& Q) const;

    /**
     * split the pixel in YIQ.
     * YIQ splitting produces unnormalized values !
     * @param pixel the pixel to be splitted
     * @param Y the perceived luminance
     * @param I color information and some luminance
     * @param Q color information and some luminance
     */
    virtual bool apply(const rgbaPixel& pixel,
                       float& Y,
                       float& I,
                       float& Q) const;

    /**
     * split the pixel in YIQ.
     * YIQ splitting produces unnormalized values !
     * @param pixel the pixel to be splitted
     * @param Y the perceived luminance
     * @param I color information and some luminance
     * @param Q color information and some luminance
     */
    virtual bool apply(const rgbaPixel& pixel,
                       ubyte& Y,
                       ubyte& I,
                       ubyte& Q) const;
  };


} // namespace cvr
#endif