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MATLAB MEX interface added, together with compiling instruction in the README file.
MEX interface written and tested on Windows 7 with MSVC 2010 x64.
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‎README.md

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Examples:
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To see how the code works, examine the three examples provided.
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## MATLAB interface
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A mex interface for computing AKAZE features is supplied, in the file `src/akaze.cpp`.
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To be able to use it, first compile the library as explained above. Then, you will need to compile the mex from matlab.
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The following is an example for compiling the mex on Windows 64 bit, Visual Studio 10 and OpenCV 2.4.8. from the `src` folder, type in MATLAB:
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mex akaze.cpp -Ilib -L'..\build\lib\Release\' -I'<path_to_opencv>\build\include' -L'<path_to_opencv>\build\x64\vc10\lib' -lopencv_calib3d248 -lopencv_contrib248 -lopencv_core248 -lopencv_highgui248 -lopencv_imgproc248 -lAKAZE
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For other platforms / compilers / OpenCV versions, change the above line accordingly.
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On Windows, you'll need to make sure that the corresponding OpenCV bin folder is added to your system path before staring MATLAB. e.g.:
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PATH=<path_to_opencv>\build\x64\vc10\bin
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Once the mex file is compiled successfully, type:
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akaze
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to display function help.
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## Documentation
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In the working folder, type: `doxygen`
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‎src/akaze.cpp

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//
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//=============================================================================
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// MEX Compilation example (with OpenCV 2.4.8):
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// mex akaze.cpp -Ilib -L'..\build\lib\Release\' -I'c:\files\libs\opencv\build\include' -L'c:\files\libs\opencv\build\x64\vc10\lib' -lopencv_calib3d248 -lopencv_contrib248 -lopencv_core248 -lopencv_highgui248 -lopencv_imgproc248 -lAKAZE
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//
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//=============================================================================
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//
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// AKAZE features MEX wrapper
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// Author: Zohar Bar-Yehuda
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// Date: 09/02/2014
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// Email: [email protected]
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//
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// AKAZE Features Copyright 2013, Pablo F. Alcantarilla, Jesus Nuevo
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// All Rights Reserved
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// See LICENSE for the license information
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//=============================================================================
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//
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// for help type:
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// akaze
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#include <math.h>
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#include <matrix.h>
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#include <mex.h>
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#include "AKAZE.h"
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#include "config.h"
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using namespace std;
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using namespace cv;
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/**
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* @brief This function shows the possible configuration options
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*/
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void show_input_options_help() {
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mexPrintf("A-KAZE Features\n");
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mexPrintf("Usage:\n");
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mexPrintf("[kps,desc] = akaze(gray_img, param1, value1, ...)\n\n");
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mexPrintf("Options below are not mandatory. Unless specified, default arguments are used.\n");
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mexPrintf("Scale-space parameters:\n");
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mexPrintf("soffset - Base scale offset [sigma units] (default=1.6)\n");
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mexPrintf("omax - Maximum octave of image evolution (default=4)\n");
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mexPrintf("nsublevels - Number of sublevels per octave (default=4)\n");
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mexPrintf("diffusivity - Diffusivity function. Possible values:\n");
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mexPrintf(" 0 -> Perona-Malik, g1 = exp(-|dL|^2/k^2)\n");
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mexPrintf(" 1 -> Perona-Malik, g2 = 1 / (1 + dL^2 / k^2) (default)\n");
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mexPrintf(" 2 -> Weickert diffusivity\n");
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mexPrintf(" 3 -> Charbonnier diffusivity\n");
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mexPrintf("\nFeature detection parameters:\n");
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mexPrintf("dthreshold - Feature detector threshold response for keypoints (0.001 can be a good value)\n");
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mexPrintf("\nDescriptor parameters:\n");
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mexPrintf("descriptor - Descriptor Type. Possible values:\n");
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mexPrintf(" 0 -> SURF_UPRIGHT\n");
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mexPrintf(" 1 -> SURF\n");
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mexPrintf(" 2 -> M-SURF_UPRIGHT,\n");
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mexPrintf(" 3 -> M-SURF\n");
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mexPrintf(" 4 -> M-LDB_UPRIGHT\n");
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mexPrintf(" 5 -> M-LDB (default)\n");
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mexPrintf("descriptor_channels - Descriptor Channels for M-LDB. Valid values: \n");
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mexPrintf(" 1 -> intensity\n");
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mexPrintf(" 2 -> intensity + gradient magnitude\n");
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mexPrintf(" 3 -> intensity + X and Y gradients (default)\n");
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mexPrintf("descriptor_size - Descriptor size for M-LDB in bits.\n");
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mexPrintf(" 0: means the full length descriptor (486) (default=0)\n");
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mexPrintf("\nMisc:\n");
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mexPrintf("verbose - Verbose mode. Prints calculation times and stores scale space images in ..\\output\\ folder (if exists)\n\n");
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}
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//*************************************************************************************
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//*************************************************************************************
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/**
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* @brief This function parses the parameter arguments for setting A-KAZE parameters
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* @param options Structure that contains A-KAZE settings
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*/
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int parse_input_options(AKAZEOptions& options, int nrhs, const mxArray *prhs[]) {
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if (nrhs >= 3) {
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for (int i = 1; i < nrhs; i+=2) {
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if( !mxIsChar(prhs[i]) || !mxIsNumeric(prhs[i+1])) {
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mexErrMsgIdAndTxt("akaze:badParamTypes",
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"Params must be string,value pairs.");
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return 1;
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}
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char *param_name = mxArrayToString(prhs[i]);
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if (!strcmp(param_name,"soffset")) {
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options.soffset = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"omax")) {
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options.omax = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"dthreshold")) {
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options.dthreshold = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"sderivatives")) {
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options.sderivatives = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"nsublevels")) {
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options.nsublevels = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"diffusivity")) {
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options.diffusivity = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"descriptor")) {
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options.descriptor = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"descriptor")) {
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options.descriptor = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"descriptor")) {
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options.descriptor = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"descriptor")) {
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options.descriptor = mxGetScalar(prhs[i+1]);
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continue;
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if (options.descriptor < 0 || options.descriptor > MLDB) {
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options.descriptor = MLDB;
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}
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}
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if (!strcmp(param_name,"descriptor_channels")) {
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options.descriptor_channels = mxGetScalar(prhs[i+1]);
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if (options.descriptor_channels <= 0 || options.descriptor_channels > 3) {
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options.descriptor_channels = 3;
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}
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continue;
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}
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if (!strcmp(param_name,"descriptor_size")) {
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options.descriptor_size = mxGetScalar(prhs[i+1]);
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if (options.descriptor_size < 0) {
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options.descriptor_size = 0;
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}
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continue;
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}
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if (!strcmp(param_name,"verbose")) {
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options.verbosity = mxGetScalar(prhs[i+1]);
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continue;
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}
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if (!strcmp(param_name,"save_scale_space")) {
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options.save_scale_space = mxGetScalar(prhs[i+1]);
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continue;
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}
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mexPrintf("Bad Param name: %s\n",param_name);
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mexErrMsgIdAndTxt("akaze:badParamName",
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"Bad parameter name.");
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return 1;
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}
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}
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return 0;
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}
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//*************************************************************************************
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//*************************************************************************************
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void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[]){
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// Variables
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AKAZEOptions options;
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// Variable for computation times.
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double t1 = 0.0, t2 = 0.0, tcvt = 0.0, tdet = 0.0, tdesc = 0.0;
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if (nrhs == 0) {
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show_input_options_help();
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return;
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}
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if( !mxIsUint8(prhs[0])) {
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mexErrMsgIdAndTxt("akaze:notUint8",
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"First Input must be a grayscale image of class UINT8.");
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}
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if (nrhs % 2 == 0)
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mexErrMsgIdAndTxt("akaze:badArgNum",
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"First input must be an image, followed by paramaters name,value pairs.");
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if (nrhs > 1){
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if (parse_input_options(options, nrhs, prhs)) {
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return;
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}
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}
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//Don't forget to specify image dimensions in AKAZE's options.
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options.img_width = mxGetM(prhs[0]);
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options.img_height = mxGetN(prhs[0]);
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Mat img = Mat(options.img_height, options.img_width, CV_8U, mxGetPr(prhs[0]));
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// OpenCV image is now a transposed image (because it's treated as row-major).
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Mat img_32;
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t1 = getTickCount();
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img.convertTo(img_32,CV_32F,1.0/255.0,0); // convert to float for descriptor computations
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t2 = getTickCount();
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tcvt = 1000.0*(t2-t1) / getTickFrequency();
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// Extract features.
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vector<KeyPoint> kpts;
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t1 = getTickCount();
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AKAZE evolution(options);
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evolution.Create_Nonlinear_Scale_Space(img_32);
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evolution.Feature_Detection(kpts);
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t2 = getTickCount();
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tdet = 1000.0*(t2-t1) / getTickFrequency();
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if (nlhs > 0){
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plhs[0] = mxCreateDoubleMatrix(kpts.size(),2,mxREAL);
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double* pts_ptr = mxGetPr(plhs[0]);
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for (int i = 0 ; i < kpts.size() ; i++){
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// Swap x,y back to get original coordinates
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pts_ptr[i] = kpts[i].pt.y;
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pts_ptr[kpts.size()+i] = kpts[i].pt.x;
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}
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}
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if (nlhs == 2){
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// Compute descriptors.
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Mat desc;
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t1 = getTickCount();
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evolution.Compute_Descriptors(kpts,desc);
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t2 = getTickCount();
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tdesc = 1000.0*(t2-t1) / getTickFrequency();
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if (desc.type() == CV_8UC1){
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plhs[1] = mxCreateNumericMatrix(desc.cols,desc.rows,mxUINT8_CLASS, mxREAL);
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// copy descriptors (desc will be freed on function exit)
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unsigned char* desc_ptr = (unsigned char*) mxGetPr(plhs[1]);
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unsigned char* mat_ptr = desc.ptr();
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for (int i = 0 ; i < desc.rows * desc.cols ; i++)
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desc_ptr[i] = mat_ptr[i];
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}
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else if (desc.type() == CV_32FC1){
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plhs[1] = mxCreateNumericMatrix(desc.cols,desc.rows,mxSINGLE_CLASS, mxREAL);
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// copy descriptors (desc will be freed on function exit)
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float* desc_ptr = (float*) mxGetPr(plhs[1]);
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float* mat_ptr = (float*) desc.ptr();
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for (int i = 0 ; i < desc.rows * desc.cols ; i++)
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desc_ptr[i] = mat_ptr[i];
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}
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else{
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mexErrMsgIdAndTxt("akaze:unknownDescType",
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"Unknown descriptor type.");
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return;
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}
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}
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// Summarize the computation times.
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if (options.verbosity){
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evolution.Show_Computation_Times();
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evolution.Save_Scale_Space();
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mexPrintf("Number of points: %d\n", kpts.size());
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mexPrintf("Time Conversion uint8->float: %.2f ms.\n", tcvt);
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mexPrintf("Time Detector: %.2f ms.\n", tdet);
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if (nlhs == 2)
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mexPrintf("Time Descriptor: %.2f ms.\n", tdesc);
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}
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// Mat img_rgb = Mat(Size(img.cols,img.rows),CV_8UC3);
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// cvtColor(img,img_rgb,CV_GRAY2BGR);
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// draw_keypoints(img_rgb,kpts);
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// imshow("",img_rgb);
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// waitKey(0);
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}

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