Constructor Detail

• BSpline

  public BSpline()

Method Detail

• resize1D

  public static double[] resize1D(double[] input,
                                  int n,
                                  int n1,
                                  int n2,
                                  double scale,
                                  boolean coefOrSamples)

  Ref: A. Muñoz-Barrutia, T. Blu, M. Unser, "Least-Squares Image Resizing Using Finite Differences," IEEE Transactions on Image Processing, vol. 10, n. 9, September 2001.

  Use: out(x) = input(x/scale); scale > 1 expansion; a < 1 reduction.

  Use n=n2:

  • if (n1==-1) the standard method (interpolation and resampling) is applied.
  • If (n=n1=n2), the orthogonal projection is computed. The error is the minimum in the least-squares sense.
  • If ((n1 > -1) && (n1<n2)), the oblique projection is computed. The error is slightly greater than the case above.

  Parameters:

  input - input signal

  n - degree of the interpolation spline. It can vary from 0 to 3.

  n1 - degree of the analysis spline. It can vary from -1 to 3.

  n2 - degree of the synthesis spline. It can vary from 0 to 3.

  scale - zoom factor (scale > 1 expansion; scale < 1 reduction)

  coefOrSamples - if working with coefficients coefOrSamples is true; if working with samples coefOrSamples is false

  Returns:

  out signal

• convertToSamples

  public static double[] convertToSamples(double[] coef,
                                          double[] samples)

  Convert the spline coefficients to samples

  Parameters:

  coef - input coefficients values

  samples - output samples

  Returns:

• finDiffAS

  public static double[] finDiffAS(double[] c)

  Finite Difference. Anti-symmetric input boundary conditions. Symmetric output boundary conditions.

  Parameters:

  c - input signal

  Returns:

  output signal

• resampling

  public static double[] resampling(double[] input,
                                    int nInput,
                                    int nOut,
                                    double scale,
                                    int n1,
                                    int nt)

  Geometric transform and resampling

  Parameters:

  input - input signal

  nInput - length of the input signal

  nOut - length of the resize signal

  scale - expansion/reduction

  n1 - degree of the analysis spline

  nt - (n+n1+1)

  Returns:

  re-sampled signal

• factorial

  public static int factorial(int n)

  Factorial

  Parameters:

  n -

  Returns:

  n factorial

• integAS

  public static double[] integAS(double[] c)

  Begin computation of the running sums. The input boundary conditions are anti-symmetric. The output boundary conditions are symmetric.

  Parameters:

  c - input coefficients

  Returns:

  sums

• integSA

  public static double integSA(double[] c,
                               double[] z)

  Begin computation of the running sums. The input boundary conditions are symmetric. The output boundary conditions are anti-symmetric.

  Parameters:

  c - coefficients

  z - sums

  Returns:

  mean value on the period (2*length(c)-2)

• mean

  public static double mean(double[] A)

  Calculate mean value on the period (2*length(A)-2)

  Parameters:

  A -

  Returns:

  mean value on the period (2*length(A)-2)

• convertToInterpCoef

  public static double[] convertToInterpCoef(double[] input,
                                             double[] poles,
                                             double tolerance)

  Convert to interpolation coefficients

  Parameters:

  input -

  poles -

  tolerance -

  Returns:

• initialAntiCausalCoefficient

  public static double initialAntiCausalCoefficient(double[] c,
                                                    double z)

  Get initial anti-causal coefficients

  Parameters:

  c - coefficients

  z - pole

  Returns:

  value of the initial anti-causal coefficient

• initialCausalCoefficient

  public static double initialCausalCoefficient(double[] c,
                                                double z,
                                                double tolerance)

  Initialization of causal coefficients for mirror boundary conditions

  Parameters:

  c - coefficients

  z - pole

  tolerance - accuracy

  Returns:

  value of the initial causal coefficient for the given accuracy

• tableOfPoles

  public static double[] tableOfPoles(int splineDegree)

  Recover the poles from a lookup table

  Parameters:

  splineDegree - degree of the spline

  Returns:

  Pole values

• tableOfSamples

  public static double[] tableOfSamples(int splineDegree)

  Recover the B-spline samples values from a lookup table

  Parameters:

  splineDegree - degree of the spline

  Returns:

  Value of the samples