SIFT feature detector and descriptor extractor.  
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| AFAPI void  | sift (features &feat, array &desc, const array &in, const unsigned n_layers=3, const float contrast_thr=0.04f, const float edge_thr=10.f, const float init_sigma=1.6f, const bool double_input=true, const float intensity_scale=0.00390625f, const float feature_ratio=0.05f) | 
|   | C++ Interface for SIFT feature detector and descriptor.  More...
  | 
|   | 
| AFAPI void  | gloh (features &feat, array &desc, const array &in, const unsigned n_layers=3, const float contrast_thr=0.04f, const float edge_thr=10.f, const float init_sigma=1.6f, const bool double_input=true, const float intensity_scale=0.00390625f, const float feature_ratio=0.05f) | 
|   | C++ Interface for SIFT feature detector and GLOH descriptor.  More...
  | 
|   | 
| AFAPI af_err  | af_sift (af_features *feat, af_array *desc, const af_array in, const unsigned n_layers, const float contrast_thr, const float edge_thr, const float init_sigma, const bool double_input, const float intensity_scale, const float feature_ratio) | 
|   | C++ Interface for SIFT feature detector and descriptor.  More...
  | 
|   | 
| AFAPI af_err  | af_gloh (af_features *feat, af_array *desc, const af_array in, const unsigned n_layers, const float contrast_thr, const float edge_thr, const float init_sigma, const bool double_input, const float intensity_scale, const float feature_ratio) | 
|   | C++ Interface for SIFT feature detector and GLOH descriptor.  More...
  | 
|   | 
SIFT feature detector and descriptor extractor. 
Detects features and extract descriptors using the Scale Invariant Feature Transform (SIFT), by David Lowe.
Lowe, D. G., "Distinctive Image Features from Scale-Invariant Keypoints", International Journal of Computer Vision, 60, 2, pp. 91-110, 2004.
WARNING: The SIFT algorithm is patented by the University of British Columbia, before using it, make sure you have the appropriate permission to do so. 
      
        
          | AFAPI af_err af_gloh  | 
          ( | 
          af_features *  | 
          feat,  | 
        
        
           | 
           | 
          af_array *  | 
          desc,  | 
        
        
           | 
           | 
          const af_array  | 
          in,  | 
        
        
           | 
           | 
          const unsigned  | 
          n_layers,  | 
        
        
           | 
           | 
          const float  | 
          contrast_thr,  | 
        
        
           | 
           | 
          const float  | 
          edge_thr,  | 
        
        
           | 
           | 
          const float  | 
          init_sigma,  | 
        
        
           | 
           | 
          const bool  | 
          double_input,  | 
        
        
           | 
           | 
          const float  | 
          intensity_scale,  | 
        
        
           | 
           | 
          const float  | 
          feature_ratio  | 
        
        
           | 
          ) | 
           |  | 
        
      
 
C++ Interface for SIFT feature detector and GLOH descriptor. 
- Parameters
 - 
  
    | [out] | feat | af_features object composed of arrays for x and y coordinates, score, orientation and size of selected features  | 
    | [out] | desc | Nx272 array containing extracted GLOH descriptors, where N is the number of features found by SIFT  | 
    | [in] | in | array containing a grayscale image (color images are not supported)  | 
    | [in] | n_layers | number of layers per octave, the number of octaves is computed automatically according to the input image dimensions, the original SIFT paper suggests 3  | 
    | [in] | contrast_thr | threshold used to filter out features that have low contrast, the original SIFT paper suggests 0.04  | 
    | [in] | edge_thr | threshold used to filter out features that are too edge-like, the original SIFT paper suggests 10.0  | 
    | [in] | init_sigma | the sigma value used to filter the input image at the first octave, the original SIFT paper suggests 1.6  | 
    | [in] | double_input | if true, the input image dimensions will be doubled and the doubled image will be used for the first octave  | 
    | [in] | intensity_scale | the inverse of the difference between the minimum and maximum grayscale intensity value, e.g.: if the ranges are 0-256, the proper intensity_scale value is 1/256, if the ranges are 0-1, the proper intensity-scale value is 1/1  | 
    | [in] | feature_ratio | maximum ratio of features to detect, the maximum number of features is calculated by feature_ratio * in.elements(). The maximum number of features is not based on the score, instead, features detected after the limit is reached are discarded  | 
  
   
 
 
      
        
          | AFAPI af_err af_sift  | 
          ( | 
          af_features *  | 
          feat,  | 
        
        
           | 
           | 
          af_array *  | 
          desc,  | 
        
        
           | 
           | 
          const af_array  | 
          in,  | 
        
        
           | 
           | 
          const unsigned  | 
          n_layers,  | 
        
        
           | 
           | 
          const float  | 
          contrast_thr,  | 
        
        
           | 
           | 
          const float  | 
          edge_thr,  | 
        
        
           | 
           | 
          const float  | 
          init_sigma,  | 
        
        
           | 
           | 
          const bool  | 
          double_input,  | 
        
        
           | 
           | 
          const float  | 
          intensity_scale,  | 
        
        
           | 
           | 
          const float  | 
          feature_ratio  | 
        
        
           | 
          ) | 
           |  | 
        
      
 
C++ Interface for SIFT feature detector and descriptor. 
- Parameters
 - 
  
    | [out] | feat | af_features object composed of arrays for x and y coordinates, score, orientation and size of selected features  | 
    | [out] | desc | Nx128 array containing extracted descriptors, where N is the number of features found by SIFT  | 
    | [in] | in | array containing a grayscale image (color images are not supported)  | 
    | [in] | n_layers | number of layers per octave, the number of octaves is computed automatically according to the input image dimensions, the original SIFT paper suggests 3  | 
    | [in] | contrast_thr | threshold used to filter out features that have low contrast, the original SIFT paper suggests 0.04  | 
    | [in] | edge_thr | threshold used to filter out features that are too edge-like, the original SIFT paper suggests 10.0  | 
    | [in] | init_sigma | the sigma value used to filter the input image at the first octave, the original SIFT paper suggests 1.6  | 
    | [in] | double_input | if true, the input image dimensions will be doubled and the doubled image will be used for the first octave  | 
    | [in] | intensity_scale | the inverse of the difference between the minimum and maximum grayscale intensity value, e.g.: if the ranges are 0-256, the proper intensity_scale value is 1/256, if the ranges are 0-1, the proper intensity-scale value is 1/1  | 
    | [in] | feature_ratio | maximum ratio of features to detect, the maximum number of features is calculated by feature_ratio * in.elements(). The maximum number of features is not based on the score, instead, features detected after the limit is reached are discarded  | 
  
   
 
 
      
        
          | AFAPI void af::gloh  | 
          ( | 
          features &  | 
          feat,  | 
        
        
           | 
           | 
          array &  | 
          desc,  | 
        
        
           | 
           | 
          const array &  | 
          in,  | 
        
        
           | 
           | 
          const unsigned  | 
          n_layers = 3,  | 
        
        
           | 
           | 
          const float  | 
          contrast_thr = 0.04f,  | 
        
        
           | 
           | 
          const float  | 
          edge_thr = 10.f,  | 
        
        
           | 
           | 
          const float  | 
          init_sigma = 1.6f,  | 
        
        
           | 
           | 
          const bool  | 
          double_input = true,  | 
        
        
           | 
           | 
          const float  | 
          intensity_scale = 0.00390625f,  | 
        
        
           | 
           | 
          const float  | 
          feature_ratio = 0.05f  | 
        
        
           | 
          ) | 
           |  | 
        
      
 
C++ Interface for SIFT feature detector and GLOH descriptor. 
- Parameters
 - 
  
    | [out] | feat | features object composed of arrays for x and y coordinates, score, orientation and size of selected features  | 
    | [out] | desc | Nx272 array containing extracted GLOH descriptors, where N is the number of features found by SIFT  | 
    | [in] | in | array containing a grayscale image (color images are not supported)  | 
    | [in] | n_layers | number of layers per octave, the number of octaves is computed automatically according to the input image dimensions, the original SIFT paper suggests 3  | 
    | [in] | contrast_thr | threshold used to filter out features that have low contrast, the original SIFT paper suggests 0.04  | 
    | [in] | edge_thr | threshold used to filter out features that are too edge-like, the original SIFT paper suggests 10.0  | 
    | [in] | init_sigma | the sigma value used to filter the input image at the first octave, the original SIFT paper suggests 1.6  | 
    | [in] | double_input | if true, the input image dimensions will be doubled and the doubled image will be used for the first octave  | 
    | [in] | intensity_scale | the inverse of the difference between the minimum and maximum grayscale intensity value, e.g.: if the ranges are 0-256, the proper intensity_scale value is 1/256, if the ranges are 0-1, the proper intensity-scale value is 1/1  | 
    | [in] | feature_ratio | maximum ratio of features to detect, the maximum number of features is calculated by feature_ratio * in.elements(). The maximum number of features is not based on the score, instead, features detected after the limit is reached are discarded  | 
  
   
 
 
      
        
          | AFAPI void af::sift  | 
          ( | 
          features &  | 
          feat,  | 
        
        
           | 
           | 
          array &  | 
          desc,  | 
        
        
           | 
           | 
          const array &  | 
          in,  | 
        
        
           | 
           | 
          const unsigned  | 
          n_layers = 3,  | 
        
        
           | 
           | 
          const float  | 
          contrast_thr = 0.04f,  | 
        
        
           | 
           | 
          const float  | 
          edge_thr = 10.f,  | 
        
        
           | 
           | 
          const float  | 
          init_sigma = 1.6f,  | 
        
        
           | 
           | 
          const bool  | 
          double_input = true,  | 
        
        
           | 
           | 
          const float  | 
          intensity_scale = 0.00390625f,  | 
        
        
           | 
           | 
          const float  | 
          feature_ratio = 0.05f  | 
        
        
           | 
          ) | 
           |  | 
        
      
 
C++ Interface for SIFT feature detector and descriptor. 
- Parameters
 - 
  
    | [out] | feat | features object composed of arrays for x and y coordinates, score, orientation and size of selected features  | 
    | [out] | desc | Nx128 array containing extracted descriptors, where N is the number of features found by SIFT  | 
    | [in] | in | array containing a grayscale image (color images are not supported)  | 
    | [in] | n_layers | number of layers per octave, the number of octaves is computed automatically according to the input image dimensions, the original SIFT paper suggests 3  | 
    | [in] | contrast_thr | threshold used to filter out features that have low contrast, the original SIFT paper suggests 0.04  | 
    | [in] | edge_thr | threshold used to filter out features that are too edge-like, the original SIFT paper suggests 10.0  | 
    | [in] | init_sigma | the sigma value used to filter the input image at the first octave, the original SIFT paper suggests 1.6  | 
    | [in] | double_input | if true, the input image dimensions will be doubled and the doubled image will be used for the first octave  | 
    | [in] | intensity_scale | the inverse of the difference between the minimum and maximum grayscale intensity value, e.g.: if the ranges are 0-256, the proper intensity_scale value is 1/256, if the ranges are 0-1, the proper intensity-scale value is 1/1  | 
    | [in] | feature_ratio | maximum ratio of features to detect, the maximum number of features is calculated by feature_ratio * in.elements(). The maximum number of features is not based on the score, instead, features detected after the limit is reached are discarded  |