SIFT算法 MATLAB实现

/* file: siftdescriptor ** author: Andrea Vedaldi ** description: Compute SIFT descriptors **/ /* AUTORIGHTS Copyright (c) 2006 The Regents of the University of California. All Rights Reserved. Created by Andrea Vedaldi UCLA Vision Lab - Department of Computer Science 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. */ /* REMARKS. The use of strcasecmp makes the function POSIX but not ANSI compliant. When compling with Altivec, GCC Altivec extensions are supported. */ #define LOWE_COMPATIBLE #include"mexutils.c" #include<stdlib.h> #include<math.h> #ifdef WINDOWS #include<string.h> #ifndef __cplusplus #define sqrtf(x) ((float)sqrt((double)(x))) #define powf(x,y) ((float)pow((double)(x),(double)(y))) #define fabsf(x) ((float)fabs((double)(x))) #define sinf(x) ((float)sin((double)(x))) #define cosf(x) ((float)cos((double)(x))) #define expf(x) ((float)exp((double)(x))) #define atan2f(x,y) ((float)atan2((double)(x),(double)(y))) #endif #else #include<strings.h> #endif /* Altivec and Accelerate support. * Very crude at this time. */ #if defined( MACOSX ) && defined( __ALTIVEC__ ) #include<Accelerate/Accelerate.h> typedef union { float x[4] ; vFloat vec ; } float4 ; #endif #define greater(a,b) a > b #define min(a,b) (((a)<(b))?(a):(b)) #define max(a,b) (((a)>(b))?(a):(b)) enum {SCALESPACE, NOSCALESPACE} ; enum {PROP_MAGNIF=0, PROP_NBP, PROP_NBO, PROP_UNKNOWN} ; char const * properties [4] = { "Magnif", "NumSpatialBins", "NumOrientBins", 0L } ; /** Fast fmodf for 2*PI **/ /*inline*/ float fast_mod(float th) { while(th < 0) th += 2*M_PI ; while(th > 2*M_PI) th -= 2*M_PI ; return th ; } /** Fast floor. Equivalent to (int) floor(x) **/ /*inline*/ int fast_floor(float x) { return (int)( x - ((x>=0)?0:1) ) ; } /** Normalizes in norm L_2 a descriptor. **/ void normalize_histogram(float* L_begin, float* L_end) { float* L_iter ; float norm=0.0 ; for(L_iter = L_begin; L_iter != L_end ; ++L_iter) norm += (*L_iter) * (*L_iter) ; norm = sqrtf(norm) ; /* mexPrintf("%f\n",norm) ;*/ for(L_iter = L_begin; L_iter != L_end ; ++L_iter) *L_iter /= norm ; } /** @brief MATLAB Driver. **/ void mexFunction(int nout, mxArray *out[], int nin, const mxArray *in[]) { int M,N,S=0,smin=0,K,num_levels=0 ; const int* dimensions ; const double* P_pt ; const double* G_pt ; float* descr_pt ; float* buffer_pt ; float sigma0 ; float magnif = 3.0f ; /* Spatial bin extension factor. */ int NBP = 4 ; /* Number of bins for one spatial direction (even). */ int NBO = 8 ; /* Number of bins for the ortientation. */ int mode = NOSCALESPACE ; int buffer_size=0; enum {IN_G=0,IN_P,IN_SIGMA0,IN_S,IN_SMIN} ; enum {OUT_L=0} ; /* ------------------------------------------------------------------ ** Check the arguments ** --------------------------------------------------------------- */ if (nin < 3) { mexErrMsgTxt("At least three arguments are required") ; } else if (nout > 1) { mexErrMsgTxt("Too many output arguments."); } if( !uIsRealScalar(in[IN_SIGMA0]) ) { mexErrMsgTxt("SIGMA0 should be a real scalar") ; } if(!mxIsDouble(in[IN_G]) || mxGetNumberOfDimensions(in[IN_G]) > 3) { mexErrMsgTxt("G should be a real matrix or 3-D array") ; } sigma0 = (float) *mxGetPr(in[IN_SIGMA0]) ; dimensions = mxGetDimensions(in[IN_G]) ; M = dimensions[0] ; N = dimensions[1] ; G_pt = mxGetPr(in[IN_G]) ; P_pt = mxGetPr(in[IN_P]) ; K = mxGetN(in[IN_P]) ; if( !uIsRealMatrix(in[IN_P],-1,-1)) { mexErrMsgTxt("P should be a real matrix") ; } if ( mxGetM(in[IN_P]) == 4) { /* Standard (scale space) mode */ mode = SCALESPACE ; num_levels = dimensions[2] ; if(nin < 5) { mexErrMsgTxt("Five arguments are required in standard mode") ; } if( !uIsRealScalar(in[IN_S]) ) { mexErrMsgTxt("S should be a real scalar") ; } if( !uIsRealScalar(in[IN_SMIN]) ) { mexErrMsgTxt("SMIN should be a real scalar") ; } if( !uIsRealMatrix(in[IN_P],4,-1)) { mexErrMsgTxt("When the e mode P should be a 4xK matrix.") ; } S = (int)(*mxGetPr(in[IN_S])) ; smin = (int)(*mxGetPr(in[IN_SMIN])) ; } else if ( mxGetM(in[IN_P]) == 3 ) { mode = NOSCALESPACE ; num_levels = 1 ; S = 1 ; smin = 0 ; } else { mexErrMsgTxt("P should be either a 3xK or a 4xK matrix.") ; } /* Parse the property-value pairs */ { char str [80] ; int arg = (mode == SCALESPACE) ? IN_SMIN + 1 : IN_SIGMA0 + 1 ; while(arg < nin) { int k ; if( !uIsString(in[arg],-1) ) { mexErrMsgTxt("The first argument in a property-value pair" " should be a string") ; } mxGetString(in[arg], str, 80) ; #ifdef WINDOWS for(k = 0 ; properties[k] && strcmpi(str, properties[k]) ; ++k) ; #else for(k = 0 ; properties[k] && strcasecmp(str, properties[k]) ; ++k) ; #endif switch (k) { case PROP_NBP: if( !uIsRealScalar(in[arg+1]) ) { mexErrMsgTxt("'NumSpatialBins' should be real scalar") ; } NBP = (int) *mxGetPr(in[arg+1]) ; if( NBP <= 0 || (NBP & 0x1) ) { mexErrMsgTxt("'NumSpatialBins' must be positive and even") ; } break ; case PROP_NBO: if( !uIsRealScalar(in[arg+1]) ) { mexErrMsgTxt("'NumOrientBins' should be a real scalar") ; } NBO = (int) *mxGetPr(in[arg+1]) ; if( NBO <= 0 ) { mexErrMsgTxt("'NumOrientlBins' must be positive") ; } break ; case PROP_MAGNIF: if( !uIsRealScalar(in[arg+1]) ) { mexErrMsgTxt("'Magnif' should be a real scalar") ; } magnif = (float) *mxGetPr(in[arg+1]) ; if( magnif <= 0 ) { mexErrMsgTxt("'Magnif' must be positive") ; } break ; case PROP_UNKNOWN: mexErrMsgTxt("Property unknown.") ; break ; } arg += 2 ; } } /* ------------------------------------------------------