Computes features of a label map.
The computed features are computed based solely on the properties of the objects in the label map, or, optionally, by also taking the intensities from a corresponding intensity image into account. Labels with value 0 are ignored.
Both images must be 2-D or 3-D single-channel images.
Area: Area of the region i.e. number of pixels of the region scaled by pixel-area.
Convex area: Area of the convex hull image, which is the smallest convex polygon that encloses the region.
Filled area: Area of the region with all the holes filled in.
Major axis length: The length of the major axis of the ellipse that has the same normalized second central moments as the region.
Minor axis length: The length of the minor axis of the ellipse that has the same normalized second central moments as the region.
Bounding box: Bounding box (min_row, min_col, max_row, max_col). Pixels belonging to the bounding box are in the half-open interval [min_row; max_row) and [min_col; max_col).
Centroid: Centroid coordinates in separate columns centroid_x, centroid_y, and centroid_z when processing 3-D data.
Eccentricity: Eccentricity of the ellipse that has the same second-moments as the region. The eccentricity is the ratio of the focal distance (distance between focal points) over the major axis length. The value is in the interval [0, 1). When it is 0, the ellipse becomes a circle.
Equivalent diameter: The diameter of a circle with the same area as the region.
Euler number: Euler characteristic of the set of non-zero pixels. Computed as number of connected components subtracted by number of holes (input.ndim connectivity). In 3-D, number of connected components plus number of holes subtracted by number of tunnels.
Extent: Ratio of pixels in the region to pixels in the total bounding box. Computed as area / (rows * cols).
Inertia tensor eigenvalues: The eigenvalues of the inertia tensor in decreasing order.
Moments: Spatial moments up to 3rd order: m_ij = sum{ array(row, col) * row^i * col^j } where the sum is over the row, col coordinates of the region.
Moments Hu: Hu moments (translation, scale and rotation invariant).
Orientation: Angle between the vertical axis (rows) and the major axis of the ellipse that has the same second moments as the region, ranging from -pi/2 to pi/2 counter-clockwise.
Perimeter: Perimeter of object which approximates the contour as a line through the centers of border pixels using a 4-connectivity. Generalizes to the surface of an object in 3-D, which uses a different approximation.
Solidity: Ratio of pixels in the region to pixels of the convex hull image.