Documentation>MATLAB API>SIFT - vl_liop

D = VL_LIOP(I) computes the LIOP descriptor of an image I, as described by [1]. I is a gray-scale square image with odd side length of class SINGLE. D is a column vector containing the LIOP descriptor of I. Note that LIOP is also integrated in the VL_COVDET() function for feature extraction.

VL_LIOP() accepts the following options:

NumNeighbours 4

Set the number of neighbours sampled to construct the order pattern of each image pixel.

Radius 5

Set the radius of the circular neighbourhood used to sampled the local order pattern of each pixel.

NumSpatialBins 6

Set the number of spatial pooling regions. The LIOP descriptor has dimension factorial(NumNeighbours) * NumSpatialBins.

IntensityThreshold -0.02

Set the intensity threshold used to weight order patterns as they are pooled into a histogram. A negative value is interpreted as a fraction of the difference between the maximum and minimum intensity in each local patch.


If specified, be verbose


[1] Z. Wang, B. Fan, F. Wu. Local Intensity Order Pattern for feature description. In ICCV, 2011