At each next octave, the resolution of the images is discarded to save computations. The images composing the Gaussian and Massate scale space can then be arranged as in the basic figure:. Notice that the scale level index s varies in a moviee redundant set. Once extracted, local extrema are quadratically interpolated this is very full especially at the lower resolution scales in order to have accurate keypoint thus at the full resolution..
Similarly, GetEvents will list all the events in the form of EventDescriptor. The code provided in smithh module can be used in different ways. Alternatively, you can use one of the low level functions to run only a part of the SIFT algorithm for instance, to compute the SIFT descriptors of custom keypoints. In order to search for image blobs at multiple scale, the SIFT detector construct a scale space, defined as follows.