sift.ipp

// file:        sift.ipp
// author:      Andrea Vedaldi
// description: Sift inline members definition

// AUTORIGHTS
// Copyright (c) 2006 The Regents of the University of California
// All Rights Reserved.
// 
// Created by Andrea Vedaldi (UCLA VisionLab)
// 
// Permission to use, copy, modify, and distribute this software and its
// documentation for educational, research and non-profit purposes,
// without fee, and without a written agreement is hereby granted,
// provided that the above copyright notice, this paragraph and the
// following three paragraphs appear in all copies.
// 
// This software program and documentation are copyrighted by The Regents
// of the University of California. The software program and
// documentation are supplied "as is", without any accompanying services
// from The Regents. The Regents does not warrant that the operation of
// the program will be uninterrupted or error-free. The end-user
// understands that the program was developed for research purposes and
// is advised not to rely exclusively on the program for any reason.
// 
// This software embodies a method for which the following patent has
// been issued: "Method and apparatus for identifying scale invariant
// features in an image and use of same for locating an object in an
// image," David G. Lowe, US Patent 6,711,293 (March 23,
// 2004). Provisional application filed March 8, 1999. Asignee: The
// University of British Columbia.
// 
// IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
// FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
// INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND
// ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN
// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. THE UNIVERSITY OF
// CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
// BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE
// MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

/** @brief Get width of an octave
 ** @param width of octave @a o.
 **/
inline
int     
VL::Sift::getOctaveWidth(int o) const
{
  assert( omin <= o && o < omin + O ) ;
  return (o >= 0) ? (width >> o) : (width << -o) ;
}

/** @brief Get height of an octave
 ** @param height of octave @a o.
 **/
inline
int
VL::Sift::getOctaveHeight(int o) const
{
  assert( omin <= o && o < omin + O ) ;
  return (o >= 0) ? (height >> o) : (height << -o) ;
}

/** @brief Get octave
 ** @param pointer to octave @a o.
 **/
inline
float * 
VL::Sift::getOctave(int o) 
{
  assert( omin <= o && o < omin + O ) ;
  return octaves[o-omin] ;
}
 
/** @brief Get level
 ** @param pointer to level @c (o,s).
 **/
inline
float * 
VL::Sift::getLevel(int o, int s) 
{
  assert( omin <= o && o <  omin + O ) ;
  assert( smin <= s && s <= smax     ) ;  
  return octaves[o - omin] +
    getOctaveWidth(o)*getOctaveHeight(o) * (s-smin) ;
}

/** @brief Get octave sampling period
 **/
inline
float
VL::Sift::getOctaveSamplingPeriod(int o) const
{
  return (o >= 0) ? (1 << o) : 1.0f / (1 << -o) ;
}

/** @brief Get octave sampling period
 **/
inline
float
VL::Sift::getScaleFromIndex(float o, float s) const
{
  return sigma0 * powf( 2.0f, o + s / S ) ;
}


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