D = VL_LIOP(I) compute the Liop descriptor of an image I. I is a square patch of an odd side length. Pixels belonging to the area of incircle of the patch will be used for computation. D is a column vector containing the liop descriptor of I. Implementation according to [1].

Use VL_COVDET() for computation of Liop descriptor from features frames.

VL_LIOP() accepts the following options:

Neighbours [4]

Set the number of neighbours used for computation of permutation index.

Bins [6]

Set the number of bins to which the points will be quintized according to their intensity.

(the final descriptor will be of length factorial(neighbours)*bins)

Radius [5]

Set the distance between a point and it's neighbours.

WeightThreshold [see below]

Set the weight threshold (i.e. how big must be the difference between intensities of all neighbouring points so that they influence descriptor value significantly). If not specified, the threshold is set according to the intensity values range:

      1) all values < 1    -> [0.02]
      2) all values < 255  -> [2]
      3) other             -> [maxIntensityValue * 0.02]
Verbose

If specified, be verbose

REFERENCES

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

    description. In ICCV, 2011