Object Descriptors

All the descriptors are automatically computed when the objects are extracted, except the additional descriptors: Feret Diameters, Context and Texture.

Note: The additional descriptors values are not saved in the JMicroVision Project file.

Position:

First point X: X coordinate position (image) of the upper left pixel of the object.
First point Y: Y coordinate position (image) of the upper left pixel of the object.
Box X min: X coordinate position (image) of the upper left point of the bounding box*.
Box Y min: Y coordinate position (image) of the upper left point of the bounding box*.
Box X width: Width of the bounding box*.
Box Y height: Height of the bounding box*.
Barycenter x: X coordinate position (image) of the center of gravity of the object.
Barycenter y: Y coordinate position (image) of the center of gravity of the object.

* The bounding box is the smallest rectangle that completely encompasses the whole object.

Note: The image position (0,0) is located by default in the upper left corner . However, the origin and the direction of the y axis can be modified in the Spatial Calibration tool.

Basic:

Area: Number of pixels in the object (minus any holes).
Perimeter: Length of the outline of the object (the outline of holes are not considered).
Convex area: Area of the convex hull of the object.
Convex perimeter: Perimeter of the convex outline of the object.
Number of holes: Number of holes in the object.
Holes area: Holes area of the object.
Orientation: Angle between the horizontal axis and the major axis of the ellipse equivalent to the object (0-180 degrees, counterclockwise).
Length: Caliper length along the orientation axis of the object.
Width: Caliper length along the orientation axis + 90° of the object.
Eccentricity: Ratio between the major and the minor axis of the ellipse equivalent to the object (first and second degree moments).

Moments:

All the moments describe the shape of the object.

Three central moments (normalized second-order central moments Xp Yq (p+q=2) of the object).

Central moment X1 Y1
Central moment X2 Y0
Central moment X0 Y2

Seven invariant moments (derived from normalized second and third order central moments) are invariant to translation, rotation and scaling of the object.

Invariant moment 1
Invariant moment 2
Invariant moment 3
Invariant moment 4
Invariant moment 5
Invariant moment 6
Invariant moment 7

Four invariant moments (derived from second and third order central moments) are invariant to translation, rotation, scaling and perspective projection of the object.

Invariant affine moment 1
Invariant affine moment 2
Invariant affine moment 3
Invariant affine moment 4

Ratio:

Compactness: Ratio of the area of the object to the area of a circle with the same perimeter.
Equivalent circular diameter: Diameter of a circle with the same area as that of the object.
Elongation: Ratio of the length to the width.
Ellipticity: Ratio of the area of an ellipse (formed with length and width as axes) to the area of the object.
Rectangularity: Ratio of the area of a rectangle (formed with length and width as sides) to the area of the object.
Solidity: Ratio of the area of the object to the convex area.
Convexity: Ratio of the convex perimeter to the perimeter of the object.

Feret (Additional):

Feret diameters are the distances between the parallel tangents touching opposite sides of the object. The number of Feret diameters from 0 to 180 degrees is defined by an angle (1-90 degrees).

Context (Additional):

Context is an additional object descriptor which describes the neighboring environment of the object. A Background is required to represent the environment.

Texture (Additional):

There are three texture parameters, Mean, Standard deviation and Entropy.