function?[keypointsdescriptors]?=?computeFeatures（im）
%?COMPUTEFEATURES?Compute?keypoints?and?descriptors?for?an?image
%???[KEYPOINTS?DEscriptORS]?=?COMPUTEFEAUTRES（IM）?computes?the
%???keypoints?and?descriptors?from?the?image?IM.?KEYPOINTS?is?a?4?x?K
%???matrix?with?one?column?for?keypoint?specifying?the?XY?location
%???the?SCALE?and?the?CONTRAST?of?the?keypoint.
%
%???DEscriptORS?is?a?128?x?K?matrix?of?SIFT?descriptors?of?the
%???keypoints.

%?Author:?Andrea?Vedaldi

im?=?standardizeImage（im）?;
[keypoints?descriptors]?=?vl_phow（im?‘step‘?4?‘floatdescriptors‘?true）?;