liop.c File Reference

Local Intensity Order Pattern (LIOP) descriptor - Definition. More...

#include "liop.h"
#include "mathop.h"
#include "imopv.h"
#include <string.h>
#include "qsort-def.h"

Functions
vl_index	get_permutation_index (vl_uindex *permutation, vl_size size)
	Compute permutation index. More...
VlLiopDesc *	vl_liopdesc_new (vl_int numNeighbours, vl_int numSpatialBins, float radius, vl_size sideLength)
	Create a new LIOP object instance. More...
VlLiopDesc *	vl_liopdesc_new_basic (vl_size sideLength)
	Create a new object with default parameters. More...
void	vl_liopdesc_delete (VlLiopDesc *self)
	Delete object instance. More...
void	vl_liopdesc_process (VlLiopDesc *self, float *desc, float const *patch)
	Compute liop descriptor for a patch. More...
vl_size	vl_liopdesc_get_dimension (VlLiopDesc const *self)
	Get the dimension of a LIOP descriptor. More...
vl_size	vl_liopdesc_get_num_neighbours (VlLiopDesc const *self)
	Get the number of neighbours. More...
float	vl_liopdesc_get_intensity_threshold (VlLiopDesc const *self)
	Get the intensity threshold. More...
void	vl_liopdesc_set_intensity_threshold (VlLiopDesc *self, float x)
	Set the intensity threshold. More...
double	vl_liopdesc_get_neighbourhood_radius (VlLiopDesc const *self)
	Get the neighbourhood radius. More...
vl_size	vl_liopdesc_get_num_spatial_bins (VlLiopDesc const *self)
	Get the number of spatial bins. More...

Detailed Description

Author

Hana Sarbortova

Andrea Vedaldi

Function Documentation

get_permutation_index()

vl_index get_permutation_index ( vl_uindex *  permutation, vl_size  size  )

inline

Parameters

permutation	array containing all values from 0 to (size - 1) (input/output).
size	size of the permutation array.

Returns

permutation index.

Compute the position of permutation in the lexycographcial sorting of permutations of the given size.

For example, in the lexicographical ordering, permutations of four elements are listed as [1 2 3 4], [1 2 4 3], [1 3 2 4], [1 3 4 2], [1 4 2 3], [1 4 3 2], [2 1 3 4], ..., [4 3 2 1].

The index can be computed as follows. First pick the first digit perm[1]. This is either 1,2,...,n. For each choice of the first digits, there are (n-1)! other permutations, separated therefore by (n-1)! elements in lexicographical order.

Process then the second digit perm[2]. This can be though as finding the lexycotraphical index of perm[2], ..., perm[n], a permutation of n-1 elements. This can be explicitly obtained by taking out 1 from all elements perm[i] > perm[1].

vl_liopdesc_delete()

void vl_liopdesc_delete

(

VlLiopDesc *

self

)

Parameters

self	object instance.

vl_liopdesc_get_dimension()

vl_size vl_liopdesc_get_dimension

(

VlLiopDesc const *

self

)

Parameters

self

object.

Returns

dimension.

vl_liopdesc_get_intensity_threshold()

float vl_liopdesc_get_intensity_threshold

(

VlLiopDesc const *

self

)

Parameters

self

object.

Returns

intensity threshold.

See also

liop-weighing

vl_liopdesc_get_neighbourhood_radius()

double vl_liopdesc_get_neighbourhood_radius

(

VlLiopDesc const *

self

)

Parameters

self

object.

Returns

neighbourhood radius.

vl_liopdesc_get_num_neighbours()

vl_size vl_liopdesc_get_num_neighbours

(

VlLiopDesc const *

self

)

Parameters

self

object.

Returns

number of neighbours.

vl_liopdesc_get_num_spatial_bins()

vl_size vl_liopdesc_get_num_spatial_bins

(

VlLiopDesc const *

self

)

Parameters

self

object.

Returns

number of spatial bins.

vl_liopdesc_new()

VlLiopDesc* vl_liopdesc_new	(	vl_int	numNeighbours,
		vl_int	numSpatialBins,
		float	radius,
		vl_size	sideLength
	)

Parameters

numNeighbours	number of neighbours.
numSpatialBins	number of bins.
radius	radius of the cirucal sample neighbourhoods.
sideLength	width of the input image patch (the patch is square).

Returns

new object instance.

The value of radius should be at least less than half the sideLength of the patch.

vl_liopdesc_new_basic()

VlLiopDesc* vl_liopdesc_new_basic

(

vl_size

sideLength

)

Parameters

sideLength

size of the patches to be processed.

Returns

new object.

See also

vl_liopdesc_new.

vl_liopdesc_process()

void vl_liopdesc_process	(	VlLiopDesc *	self,
		float *	desc,
		float const *	patch
	)

Parameters

self	object instance
desc	descriptor to be computed (output).
patch	patch to process

Use vl_liopdesc_get_dimension to get the size of the descriptor desc.

vl_liopdesc_set_intensity_threshold()

void vl_liopdesc_set_intensity_threshold	(	VlLiopDesc *	self,
		float	x
	)

Parameters

self	object.
x	intensity threshold.

If non-negative, the threshold as is is used when comparing intensities. If negative, the absolute value of the specified number is multipled by the maximum intensity difference inside a patch to obtain the threshold.

See also

liop-weighing