Field Detail

• state

  public FloatArray2DScaleOctave.State state

• width

  public int width

• height

  public int height

• STEPS

  public int STEPS

  steps per octave an octave consists of STEPS + 3 images to be

• SIGMA

  public float[] SIGMA

  sigma of gaussian kernels corresponding to the steps of the octave the first member is the sigma of the gaussian kernel that is assumed to be the generating kernel of the first gaussian image instance of the octave

Constructor Detail

• FloatArray2DScaleOctave

  public FloatArray2DScaleOctave(FloatArray2D img,
                                 int steps,
                                 float initial_sigma)

  Constructor

  Parameters:

  img - image being the first gaussian instance of the scale octave img must be a 2d-array of float values in range [0.0f, ..., 1.0f]

  initial_sigma - inital gaussian sigma

• FloatArray2DScaleOctave

  public FloatArray2DScaleOctave(FloatArray2D img,
                                 float[] sigma,
                                 float[] sigma_diff,
                                 float[][] kernel_diff)

  Constructor faster initialisation with precomputed gaussian kernels

  Parameters:

  img - image being the first gaussian instance of the scale octave

  sigma - initial_sigma inital gaussian sigma

Method Detail

• getL

  public FloatArray2D[] getL()

• getL

  public FloatArray2D getL(int i)

• getD

  public FloatArray2D[] getD()

• getD

  public FloatArray2D getD(int i)

• getL1

  public FloatArray2D[] getL1(int i)

  get the gradients of the corresponding gaussian image, generates it on demand, if not yet available.

  Parameters:

  i - index will not be checked for efficiency reasons, so take care that it is within a valid range

  Returns:

  reference to the gradients

• buildStub

  public void buildStub()

  build only the gaussian image with 2 * INITIAL_SIGMA Use this method for the partial creation of an octaved scale space without creating each scale octave. Like proposed by Lowe \citep{Lowe04}, you can use this image to build the next scale octave. Taking every second pixel of this image, you get a gaussian image with INITIAL_SIGMA of the half image size.

• build

  public boolean build()

  build the scale octave

• clear

  public void clear()

  clear the scale octave to save memory

• downsample

  public static void downsample(FloatArray2D src,
                                FloatArray2D dst)

  Downsample src by simply using every second pixel into dst.

  For efficiency reasons, the dimensions of dst are not checked, that is, you have to take care, that

  
   dst.width == src.width / 2 + src.width % 2 &&
   dst.height == src.height / 2 + src.height % 2 .
   

  Parameters:

  src - the source image

  dst - destination image

• upsample

  public static void upsample(FloatArray2D src,
                              FloatArray2D dst)

  Upsample src by linearly interpolating into dst.

  For efficiency reasons, the dimensions of dst are not checked, that is, you have to take care, that

  
   src.width == dst.width / 2 + dst.width % 2 &&
   src.height == dst.height / 2 + dst.height % 2 .
   

  Parameters:

  src - the source image

  dst - destination image