finds key features in image and returns their coordinates.

gives the specified property prop for each keypoint.

Details and OptionsDetails and Options

  • ImageKeypoints[image] finds keypoints in image with image dimensions {w,h} and returns their image coordinates as a list of the form {{x1,y1},{x2,y2},}.
  • The following properties can be specified:
  • "Position"image coordinates {x,y} in the range ,
    "PixelPosition"pixel coordinates {x,y} in the range ,
    "Scale"keypoint scale
    "Orientation"orientation angle, given in radians
    "Strength"blob response, given as a positive number
    "ContrastSign" if the keypoint is lighter than its surroundings, otherwise
    "Descriptor"SURF keypoint descriptor, given as a unit vector of length 64
    "OrientedDescriptor"oriented descriptor
  • ImageKeypoints sorts the results based on the "Strength" property of the keypoints.
  • ImageKeypoints[image,{prop1,prop2,}] returns multiple properties.
  • The feature descriptors returned by ImageKeypoints are numerically robust against translation, rotation, and scale changes.
  • The following options can be specified:
  • KeypointStrength0minimum strength of the keypoints
    MaxFeaturesAllmaximum number of keypoints
  • With a setting MaxFeatures->n, at most n keypoints with largest "Strength" are returned.
  • ImageKeypoints uses the SURF keypoint detection method.
Introduced in 2010
| Updated in 2014