lib/ccv_sift.c

ccv_sift

void ccv_sift(ccv_dense_matrix_t* a, ccv_array_t **_keypoints, ccv_dense_matrix_t** _desc, int type, ccv_sift_param_t params)

Compute SIFT key-points.

• a : the input matrix.
• keypoints : the array of key-points, a ccv_keypoint_t structure.
• desc : the descriptor for each key-point.
• type : the type of the descriptor, if 0, ccv will default to CCV_32F.
• params : a ccv_sift_param_t structure that defines various aspect of SIFT function.

ccv_sift_param_t

• up2x : if upscale the image for better SIFT accuracy.
• noctaves : number of octaves.
• nlevels : number of levels for each octaves.
• edge_threshold : above this threshold, it will be recognized as edge as be ignored.
• peak_threshold : above this threshold, it will be recognized as potential feature point.
• norm_threshold : if norm of the descriptor is smaller than threshold, it ill be ignored.

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