PerceptualHash class

Algorithm class for comparing images with the perceptual hash method

Images are grayscaled and resized to 32x32. Then they are passed through a 1-dimension discrete cosine transformation. The top 8x8 is only accounted for since it gives the generalized frequency of the image. With this, a hash is created.

  • Applications in digital forensics, copyright protection, and media file search
  • Works well with images of any dimension and aspect ratio
  • Comparing image fingerprints
  • Images can be rotated
  • Does not handle transparent pixels
  • Returns percentage diffence (0.0 - no difference, 1.0 - 100% difference)
Inheritance

Constructors

PerceptualHash()

Properties

hashCode → int
The hash code for this object.
no setterinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited

Methods

average(List pixels) → num
Helper funciton to compute the average of an array after dct caclulations
calcPhash(List pixelList) → String
Helper function which computes a binary hash of a List of Pixel
calculateDCT(List matrix) → List
Helper function to perform 1D discrete cosine tranformation on a matrix
compare(Image src1, Image src2) → double
Resize and grayscale images
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
override
unit8ListToMatrix(List pixelList) → List
Helper function to convert a Unit8List to a nD matrix

Operators

operator ==(Object other) → bool
The equality operator.
inherited