symmetrysymmetrySymmetrySymmetrysymmetry (Operator)


symmetrysymmetrySymmetrySymmetrysymmetry — Symmetry of gray values along a row.


symmetry(Image : ImageSymmetry : MaskSize, Direction, Exponent : )

Herror symmetry(const Hobject Image, Hobject* ImageSymmetry, const Hlong MaskSize, double Direction, double Exponent)

Herror T_symmetry(const Hobject Image, Hobject* ImageSymmetry, const Htuple MaskSize, const Htuple Direction, const Htuple Exponent)

void Symmetry(const HObject& Image, HObject* ImageSymmetry, const HTuple& MaskSize, const HTuple& Direction, const HTuple& Exponent)

HImage HImage::Symmetry(Hlong MaskSize, double Direction, double Exponent) const

static void HOperatorSet.Symmetry(HObject image, out HObject imageSymmetry, HTuple maskSize, HTuple direction, HTuple exponent)

HImage HImage.Symmetry(int maskSize, double direction, double exponent)

def symmetry(image: HObject, mask_size: int, direction: float, exponent: float) -> HObject


symmetrysymmetrySymmetrySymmetrySymmetrysymmetry calculates the symmetry along a line. For each pixel the gray values of both sides of the line are compared: The absolute value of the differences of gray values with same distance to the pixel is computed. Each of these differences is weighted by the exponent (after division by 255) and then summed up. Pixels with a high symmetry have large gray values.


Currently only horizontal search lines are implemented. Note that the parameter DirectionDirectionDirectionDirectiondirectiondirection exists for future extensions and can currently only have the value 0.0.

Note that filter operators may return unexpected results if an image with a reduced domain is used as input. Please refer to the chapter Filters.

Execution Information


ImageImageImageImageimageimage (input_object)  (multichannel-)image(-array) objectHImageHObjectHImageHobject (byte)

Input image.

ImageSymmetryImageSymmetryImageSymmetryImageSymmetryimageSymmetryimage_symmetry (output_object)  (multichannel-)image(-array) objectHImageHObjectHImageHobject * (byte)

Symmetry image.

MaskSizeMaskSizeMaskSizeMaskSizemaskSizemask_size (input_control)  number HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Extension of search area.

Default value: 40

Suggested values: 3, 5, 7, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 100, 120, 140, 180

Typical range of values: 3 ≤ MaskSize MaskSize MaskSize MaskSize maskSize mask_size ≤ 1000

Minimum increment: 1

Recommended increment: 2

DirectionDirectionDirectionDirectiondirectiondirection (input_control)  number HTuplefloatHTupleHtuple (real) (double) (double) (double)

Angle of test direction.

Default value: 0.0

Suggested values: 0.0

Typical range of values: 0.0 ≤ Direction Direction Direction Direction direction direction ≤ 0.0

ExponentExponentExponentExponentexponentexponent (input_control)  number HTuplefloatHTupleHtuple (real) (double) (double) (double)

Exponent for weighting.

Default value: 0.5

Suggested values: 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 0.8, 0.9, 1.0

Typical range of values: 0.05 ≤ Exponent Exponent Exponent Exponent exponent exponent ≤ 1.0

Minimum increment: 0.01

Recommended increment: 0.1

Restriction: 0 < Exponent && Exponent <= 1

Example (HDevelop)



If the parameter values are correct the operator symmetrysymmetrySymmetrySymmetrySymmetrysymmetry returns the value 2 (H_MSG_TRUE) The behavior in case of empty input (no input images available) is set via the operator set_system(::'no_object_result',<Result>:)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>). If necessary an exception is raised.

Possible Successors