CImagePyramid.h

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/* +---------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)               |
   |                          http://www.mrpt.org/                             |
   |                                                                           |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file        |
   | See: http://www.mrpt.org/Authors - All rights reserved.                   |
   | Released under BSD License. See details in http://www.mrpt.org/License    |
   +---------------------------------------------------------------------------+ */

#ifndef __mrpt_vision_image_pyramid_H
#define __mrpt_vision_image_pyramid_H

#include <mrpt/utils/CImage.h>

#include <mrpt/vision/link_pragmas.h>

namespace mrpt
{
        namespace vision
        {
                /** Holds and builds a pyramid of images: starting with an image at full resolution (octave=1), it builds
                  *  a number of half-resolution images: octave=2 at 1/2 , octave=3 at 1/2^2, octave=N at 1/2^(N-1).
                  *
                  *  Color (RGB) or grayscale pyramids can be built from color input images; only grayscale pyramids can be built from
                  *   grayscale images.
                  *
                  *  The algorithm to halve the images can be either a 1:2 decimation or a smooth filter (arithmetic mean of every 4 pixels).
                  *
                  *  Pyramids are built by invoking the method \a buildPyramid() or \a buildPyramidFast()
                  *
                  * Example of usage:
                  * \code
                  *   CImagePyramid  pyr;
                  *
                  *   CImage img = ...
                  *
                  *   pyr.buildPyramid(
                  *      img,
                  *      4,    // num. of octaves
                  *      true  // smooth
                  *      );
                  *
                  *   pyr.images[0].saveToFile("pyr0.jpg");
                  *   pyr.images[1].saveToFile("pyr1.jpg");
                  *   ...
                  * \endcode
                  *
                  *  \note Both converting to grayscale and building the octave images have SSE2-optimized implementations (if available).
                  *
                  * \sa mrpt::utils::CImage
                  * \ingroup mrpt_vision_grp 
                  */
                class VISION_IMPEXP CImagePyramid
                {
                public:
                        CImagePyramid();   //!< Default constructor, does nothing
                        ~CImagePyramid();  //!< Destructor, frees the stored images.

                        /** Fills the vector \a images with the different octaves built from the input image.
                          *  \param[in] img The input image. Can be either color or grayscale.
                          *  \param[in] nOctaves Number of octaves to build. 1 means just the original image, 2 means the original plus the 1/2 image, etc.
                          *  \param[in] smooth_halves If true, use an arithmetic mean of every 2x2 pixel block when downsampling.
                          *  \param[in] convert_grayscale If true, the pyramid is built in grayscale even for color input images.
                          * \sa buildPyramidFast
                          */
                        void buildPyramid(const mrpt::utils::CImage &img, const size_t nOctaves, const bool smooth_halves = true, const bool convert_grayscale = false );

                        /**  Exactly like \a buildPyramid(), but if the input image has not to be converted from RGB to grayscale, the image data buffer is *reutilized*
                          *   for the 1st octave in \a images[0], emptying the input image.
                          * \sa buildPyramid
                          */
                        void buildPyramidFast(mrpt::utils::CImage &img, const size_t nOctaves, const bool smooth_halves = true, const bool convert_grayscale = false );

                        /** The individual images:
                          *  - images[0]: 1st octave (full-size)
                          *  - images[1]: 2nd octave (1/2 size)
                          *  - images[2]: 3rd octave (1/4 size)
                          */
                        std::vector<mrpt::utils::CImage>  images;
                };

        }
}

#endif