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

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

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