Class Feature2D

Abstract base class for 2D image feature detectors and descriptor extractors

Inheritance
System.Object
DisposableObject
DisposableCvObject
Algorithm
Feature2D
AgastFeatureDetector
AKAZE
BRISK
FastFeatureDetector
SIFT
GFTTDetector
KAZE
MSER
ORB
SimpleBlobDetector
BriefDescriptorExtractor
FREAK
LATCH
LUCID
StarDetector
SURF
Implements
Inherited Members
Namespace: OpenCvSharp
Assembly: OpenCvSharp.dll
Syntax
public class Feature2D : Algorithm, ICvPtrHolder

Constructors

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Feature2D()

Declaration
protected Feature2D()

Properties

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DefaultNorm

Declaration
public virtual int DefaultNorm { get; }
Property Value
Type Description
System.Int32
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DescriptorSize

Declaration
public virtual int DescriptorSize { get; }
Property Value
Type Description
System.Int32
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DescriptorType

Declaration
public virtual int DescriptorType { get; }
Property Value
Type Description
System.Int32

Methods

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Compute(IEnumerable<Mat>, ref KeyPoint[][], IEnumerable<Mat>)

Compute the descriptors for a keypoints collection detected in image collection.

Declaration
public virtual void Compute(IEnumerable<Mat> images, ref KeyPoint[][] keypoints, IEnumerable<Mat> descriptors)
Parameters
Type Name Description
IEnumerable<Mat> images

Image collection.
OpenCvSharp.KeyPoint[][] keypoints

Input keypoints collection. keypoints[i] is keypoints detected in images[i]. Keypoints for which a descriptor cannot be computed are removed.
IEnumerable<Mat> descriptors

Descriptor collection. descriptors[i] are descriptors computed for set keypoints[i].
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Compute(InputArray, ref KeyPoint[], OutputArray)

Compute the descriptors for a set of keypoints in an image.

Declaration
public virtual void Compute(InputArray image, ref KeyPoint[] keypoints, OutputArray descriptors)
Parameters
Type Name Description
InputArray image

The image.
OpenCvSharp.KeyPoint[] keypoints

The input keypoints. Keypoints for which a descriptor cannot be computed are removed.
OutputArray descriptors

Computed descriptors. Row i is the descriptor for KeyPoint i.
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Detect(IEnumerable<Mat>, Nullable<IEnumerable<Mat>>)

Detect keypoints in an image set.

Declaration
public KeyPoint[][] Detect(IEnumerable<Mat> images, IEnumerable<Mat>? masks = null)
Parameters
Type Name Description
IEnumerable<Mat> images

Image collection.
System.Nullable<IEnumerable<Mat>> masks

Masks for image set. masks[i] is a mask for images[i].
Returns
Type Description
OpenCvSharp.KeyPoint[][]

Collection of keypoints detected in an input images. keypoints[i] is a set of keypoints detected in an images[i].
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Detect(InputArray, Mat)

Detect keypoints in an image.

Declaration
public KeyPoint[] Detect(InputArray image, Mat mask = null)
Parameters
Type Name Description
InputArray image

The image.
Mat mask

Mask specifying where to look for keypoints (optional). Must be a char matrix with non-zero values in the region of interest.
Returns
Type Description
OpenCvSharp.KeyPoint[]

The detected keypoints.
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Detect(Mat, Mat)

Detect keypoints in an image.

Declaration
public KeyPoint[] Detect(Mat image, Mat mask = null)
Parameters
Type Name Description
Mat image

The image.
Mat mask

Mask specifying where to look for keypoints (optional). Must be a char matrix with non-zero values in the region of interest.
Returns
Type Description
OpenCvSharp.KeyPoint[]

The detected keypoints.
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DetectAndCompute(InputArray, InputArray, out KeyPoint[], OutputArray, Boolean)

Detects keypoints and computes the descriptors

Declaration
public virtual void DetectAndCompute(InputArray image, InputArray mask, out KeyPoint[] keypoints, OutputArray descriptors, bool useProvidedKeypoints = false)
Parameters
Type Name Description
InputArray image
InputArray mask
OpenCvSharp.KeyPoint[] keypoints
OutputArray descriptors
System.Boolean useProvidedKeypoints
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Empty()

Return true if detector object is empty

Declaration
public virtual bool Empty()
Returns
Type Description
System.Boolean
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GetDefaultName()

Declaration
public override string GetDefaultName()
Returns
Type Description
System.String
Overrides
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Read(String)

Declaration
public void Read(string fileName)
Parameters
Type Name Description
System.String fileName
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Write(String)

Declaration
public void Write(string fileName)
Parameters
Type Name Description
System.String fileName

Implements