src/main/java/org/apache/pdfbox/jbig2/image/Filter.java - pdfbox-jbig2 - Git at Google

 /**
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package org.apache.pdfbox.jbig2.image;


 abstract class Filter {

   /**
    * Find a filter name by its type.
    *
    * @param type the filter type
    * @return filter name
    */
   public static String nameByType(final FilterType type) {
     if (type == null)
       throw new IllegalArgumentException("type must not be null");
     return type.name();
   }

   /**
    * Find a filter type by its name.
    *
    * @param name the filter name
    * @return filter type
    */
   public static FilterType typeByName(final String name) {
     if (name == null)
       throw new IllegalArgumentException("name must not be null");
     return FilterType.valueOf(name);
   }

   /**
    * Find a filter by its type.
    *
    * @param type the filter type
    * @return the Filter
    */
   public static Filter byType(final FilterType type) {
     switch (type){
       case Bessel :
         return new Bessel();
       case Blackman :
         return new Blackman();
       case Box :
         return new Box();
       case Catrom :
         return new Catrom();
       case Cubic :
         return new Cubic();
       case Gaussian :
         return new Gaussian();
       case Hamming :
         return new Hamming();
       case Hanning :
         return new Hanning();
       case Hermite :
         return new Hermite();
       case Lanczos :
         return new Lanczos();
       case Mitchell :
         return new Mitchell();
       case Point :
         return new Point();
       case Quadratic :
         return new Quadratic();
       case Sinc :
         return new Sinc();
       case Triangle :
         return new Triangle();
     }
     throw new IllegalArgumentException("No filter for given type.");
   }

   public static final class Bessel extends Filter {
     public Bessel() {
       super(false, 3.2383, 1.0);
     }

     private double J1(final double x) {
       double p, q;

       int i;

       final double Pone[] = {
           0.581199354001606143928050809e+21, -0.6672106568924916298020941484e+20, 0.2316433580634002297931815435e+19,
           -0.3588817569910106050743641413e+17, 0.2908795263834775409737601689e+15, -0.1322983480332126453125473247e+13,
           0.3413234182301700539091292655e+10, -0.4695753530642995859767162166e+7, 0.270112271089232341485679099e+4
       }, Qone[] = {
           0.11623987080032122878585294e+22, 0.1185770712190320999837113348e+20, 0.6092061398917521746105196863e+17,
           0.2081661221307607351240184229e+15, 0.5243710262167649715406728642e+12, 0.1013863514358673989967045588e+10,
           0.1501793594998585505921097578e+7, 0.1606931573481487801970916749e+4, 0.1e+1
       };

       p = Pone[8];
       q = Qone[8];
       for (i = 7; i >= 0; i--) {
         p = p * x * x + Pone[i];
         q = q * x * x + Qone[i];
       }
       return p / q;
     }

     private double P1(final double x) {
       double p, q;

       int i;

       final double Pone[] = {
           0.352246649133679798341724373e+5, 0.62758845247161281269005675e+5, 0.313539631109159574238669888e+5,
           0.49854832060594338434500455e+4, 0.2111529182853962382105718e+3, 0.12571716929145341558495e+1
       }, Qone[] = {
           0.352246649133679798068390431e+5, 0.626943469593560511888833731e+5, 0.312404063819041039923015703e+5,
           0.4930396490181088979386097e+4, 0.2030775189134759322293574e+3, 0.1e+1
       };

       p = Pone[5];
       q = Qone[5];
       for (i = 4; i >= 0; i--) {
         p = p * (8.0 / x) * (8.0 / x) + Pone[i];
         q = q * (8.0 / x) * (8.0 / x) + Qone[i];
       }
       return p / q;
     }

     private double Q1(final double x) {
       double p, q;

       int i;

       final double Pone[] = {
           0.3511751914303552822533318e+3, 0.7210391804904475039280863e+3, 0.4259873011654442389886993e+3,
           0.831898957673850827325226e+2, 0.45681716295512267064405e+1, 0.3532840052740123642735e-1
       }, Qone[] = {
           0.74917374171809127714519505e+4, 0.154141773392650970499848051e+5, 0.91522317015169922705904727e+4,
           0.18111867005523513506724158e+4, 0.1038187585462133728776636e+3, 0.1e+1
       };

       p = Pone[5];
       q = Qone[5];
       for (i = 4; i >= 0; i--) {
         p = p * (8.0 / x) * (8.0 / x) + Pone[i];
         q = q * (8.0 / x) * (8.0 / x) + Qone[i];
       }
       return p / q;
     }

     private double BesselOrderOne(double x) {
       double p, q;

       if (x == 0.0)
         return 0.0;
       p = x;
       if (x < 0.0)
         x = -x;
       if (x < 8.0)
         return p * J1(x);
       q = Math.sqrt(2.0 / (Math.PI * x))
           * (P1(x) * (1.0 / Math.sqrt(2.0) * (Math.sin(x) - Math.cos(x))) - 8.0 / x * Q1(x)
               * (-1.0 / Math.sqrt(2.0) * (Math.sin(x) + Math.cos(x))));
       if (p < 0.0)
         q = -q;
       return q;
     }

     @Override
     public double f(final double x) {
       if (x == 0.0)
         return Math.PI / 4.0;
       return BesselOrderOne(Math.PI * x) / (2.0 * x);
     }
   }

   public static final class Blackman extends Filter {
     @Override
     public double f(final double x) {
       return 0.42 + 0.50 * Math.cos(Math.PI * x) + 0.08 * Math.cos(2.0 * Math.PI * x);
     }
   }

   public static class Box extends Filter {
     public Box() {
       super(true, .5, 1.0);
     }

     public Box(final double supp) {
       super(true, supp, 1.0);
     }

     @Override
     public double f(final double x) {
       if (x >= -0.5 && x < 0.5)
         return 1.0;
       return 0.0;
     }
   }

   public static final class Point extends Box {
     public Point() {
       super(0);
     }

     @Override
     public double fWindowed(double x) {
       // don't apply windowing as we have a radius of zero.
       return super.f(x);
     }
   }

   public static final class Catrom extends Filter {
     public Catrom() {
       super(true, 2.0, 1.0);
     }

     @Override
     public double f(double x) {
       if (x < 0)
         x = -x;
       if (x < 1.0)
         return 0.5 * (2.0 + x * x * (-5.0 + x * 3.0));
       if (x < 2.0)
         return 0.5 * (4.0 + x * (-8.0 + x * (5.0 - x)));
       return 0.0;
     }
   }

   public static final class Cubic extends Filter {
     public Cubic() {
       super(false, 2.0, 1.0);
     }

     @Override
     public double f(double x) {
       if (x < 0)
         x = -x;
       if (x < 1.0)
         return 0.5 * x * x * x - x * x + 2.0 / 3.0;
       if (x < 2.0) {
         x = 2.0 - x;
         return 1.0 / 6.0 * x * x * x;
       }
       return 0.0;
     }
   }

   public static final class Gaussian extends Filter {
     public Gaussian() {
       super(false, 1.25, 1.0);
     }

     @Override
     public double f(final double x) {
       return Math.exp(-2.0 * x * x) * Math.sqrt(2.0 / Math.PI);
     }
   }

   public static final class Hamming extends Filter {
     @Override
     public double f(final double x) {
       return 0.54 + 0.46 * Math.cos(Math.PI * x);
     }
   }

   public static final class Hanning extends Filter {
     @Override
     public double f(final double x) {
       return 0.5 + 0.5 * Math.cos(Math.PI * x);
     }
   }

   public static final class Hermite extends Filter {
     @Override
     public double f(double x) {
       if (x < 0) {
         x = -x;
       }

       if (x < 1.0) {
         return (2.0 * x - 3.0) * x * x + 1.0;
       }
       return 0.0;
     }
   }

   public static final class Lanczos extends Filter {
     public Lanczos() {
       super(true, 3.0, 1.0);
     }

     @Override
     public double f(double x) {
       if (x < 0)
         x = -x;
       if (x < 3.0)
         return (float) (sinc(x) * sinc(x / 3.0));
       return 0.0;
     }

     private double sinc(double value) {
       if (value != 0.0f) {
         value = value * Math.PI;
         return Math.sin(value) / value;
       } else {
         return 1.0;
       }
     }

   }

   public static final class Mitchell extends Filter {
     public Mitchell() {
       super(false, 2.0, 1.0);
     }

     @Override
     public double f(double x) {
       double b, c;

       b = 1.0 / 3.0;
       c = 1.0 / 3.0;
       if (x < 0)
         x = -x;
       if (x < 1.0) {
         x = (12.0 - 9.0 * b - 6.0 * c) * (x * x * x) + (-18.0 + 12.0 * b + 6.0 * c) * x * x + (6.0 - 2.0 * b);
         return x / 6.0;
       }
       if (x < 2.0) {
         x = (-1.0 * b - 6.0 * c) * (x * x * x) + (6.0 * b + 30.0 * c) * x * x + (-12.0 * b - 48.0 * c) * x
             + (8.0 * b + 24.0 * c);
         return x / 6.0;
       }
       return 0.0;
     }
   }

   public static final class Quadratic extends Filter {
     public Quadratic() {
       super(false, 1.5, 1.0);
     }

     @Override
     public double f(double x) {
       if (x < 0)
         x = -x;
       if (x < 0.5)
         return 0.75 - x * x;
       if (x < 1.5) {
         x -= 1.5;
         return 0.5 * x * x;
       }
       return 0.0;
     }
   }

   public static final class Sinc extends Filter {
     public Sinc() {
       super(true, 4.0, 1.0);
     }

     @Override
     public double f(double x) {
       x *= Math.PI;
       if (x != 0.0)
         return Math.sin(x) / x;
       return 1.0;
     }
   }

   public static final class Triangle extends Filter {
     @Override
     public double f(double x) {
       if (x < 0.0)
         x = -x;
       if (x < 1.0)
         return 1.0 - x;
       return 0.0;
     }
   }

   /**
    * is this filter cardinal? ie, does func(x) = (x==0) for integer x?
    */
   final boolean cardinal;

   /** radius of nonzero portion */
   double support;

   /** blur factor (1=normal) */
   double blur;

   protected Filter() {
     this(true, 1.0, 1.0);
   }

   protected Filter(final boolean cardinal, final double support, final double blur) {
     this.cardinal = cardinal;
     this.support = support;
     this.blur = blur;
   }

   public double fWindowed(double x) {
     return x < -support || x > support ? 0 : f(x);
   }

   public abstract double f(double x);

   /**
    * Return the filter name.
    *
    * @return the filter's name
    */
   public String getName() {
     return getClass().getSimpleName();
   }

   /**
    * @return the support
    */
   public double getSupport() {
     return support;
   }

   /**
    * @param support the support to set
    */
   public void setSupport(final double support) {
     this.support = support;
   }

   /**
    * @return the blur
    */
   public double getBlur() {
     return blur;
   }

   /**
    * @param blur the blur to set
    */
   public void setBlur(final double blur) {
     this.blur = blur;
   }
 }
	/**
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package org.apache.pdfbox.jbig2.image;


	abstract class Filter {

	/**
	* Find a filter name by its type.
	*
	* @param type the filter type
	* @return filter name
	*/
	public static String nameByType(final FilterType type) {
	if (type == null)
	throw new IllegalArgumentException("type must not be null");
	return type.name();
	}

	/**
	* Find a filter type by its name.
	*
	* @param name the filter name
	* @return filter type
	*/
	public static FilterType typeByName(final String name) {
	if (name == null)
	throw new IllegalArgumentException("name must not be null");
	return FilterType.valueOf(name);
	}

	/**
	* Find a filter by its type.
	*
	* @param type the filter type
	* @return the Filter
	*/
	public static Filter byType(final FilterType type) {
	switch (type){
	case Bessel :
	return new Bessel();
	case Blackman :
	return new Blackman();
	case Box :
	return new Box();
	case Catrom :
	return new Catrom();
	case Cubic :
	return new Cubic();
	case Gaussian :
	return new Gaussian();
	case Hamming :
	return new Hamming();
	case Hanning :
	return new Hanning();
	case Hermite :
	return new Hermite();
	case Lanczos :
	return new Lanczos();
	case Mitchell :
	return new Mitchell();
	case Point :
	return new Point();
	case Quadratic :
	return new Quadratic();
	case Sinc :
	return new Sinc();
	case Triangle :
	return new Triangle();
	}
	throw new IllegalArgumentException("No filter for given type.");
	}

	public static final class Bessel extends Filter {
	public Bessel() {
	super(false, 3.2383, 1.0);
	}

	private double J1(final double x) {
	double p, q;

	int i;

	final double Pone[] = {
	0.581199354001606143928050809e+21, -0.6672106568924916298020941484e+20, 0.2316433580634002297931815435e+19,
	-0.3588817569910106050743641413e+17, 0.2908795263834775409737601689e+15, -0.1322983480332126453125473247e+13,
	0.3413234182301700539091292655e+10, -0.4695753530642995859767162166e+7, 0.270112271089232341485679099e+4
	}, Qone[] = {
	0.11623987080032122878585294e+22, 0.1185770712190320999837113348e+20, 0.6092061398917521746105196863e+17,
	0.2081661221307607351240184229e+15, 0.5243710262167649715406728642e+12, 0.1013863514358673989967045588e+10,
	0.1501793594998585505921097578e+7, 0.1606931573481487801970916749e+4, 0.1e+1
	};

	p = Pone[8];
	q = Qone[8];
	for (i = 7; i >= 0; i--) {
	p = p * x * x + Pone[i];
	q = q * x * x + Qone[i];
	}
	return p / q;
	}

	private double P1(final double x) {
	double p, q;

	int i;

	final double Pone[] = {
	0.352246649133679798341724373e+5, 0.62758845247161281269005675e+5, 0.313539631109159574238669888e+5,
	0.49854832060594338434500455e+4, 0.2111529182853962382105718e+3, 0.12571716929145341558495e+1
	}, Qone[] = {
	0.352246649133679798068390431e+5, 0.626943469593560511888833731e+5, 0.312404063819041039923015703e+5,
	0.4930396490181088979386097e+4, 0.2030775189134759322293574e+3, 0.1e+1
	};

	p = Pone[5];
	q = Qone[5];
	for (i = 4; i >= 0; i--) {
	p = p * (8.0 / x) * (8.0 / x) + Pone[i];
	q = q * (8.0 / x) * (8.0 / x) + Qone[i];
	}
	return p / q;
	}

	private double Q1(final double x) {
	double p, q;

	int i;

	final double Pone[] = {
	0.3511751914303552822533318e+3, 0.7210391804904475039280863e+3, 0.4259873011654442389886993e+3,
	0.831898957673850827325226e+2, 0.45681716295512267064405e+1, 0.3532840052740123642735e-1
	}, Qone[] = {
	0.74917374171809127714519505e+4, 0.154141773392650970499848051e+5, 0.91522317015169922705904727e+4,
	0.18111867005523513506724158e+4, 0.1038187585462133728776636e+3, 0.1e+1
	};

	p = Pone[5];
	q = Qone[5];
	for (i = 4; i >= 0; i--) {
	p = p * (8.0 / x) * (8.0 / x) + Pone[i];
	q = q * (8.0 / x) * (8.0 / x) + Qone[i];
	}
	return p / q;
	}

	private double BesselOrderOne(double x) {
	double p, q;

	if (x == 0.0)
	return 0.0;
	p = x;
	if (x < 0.0)
	x = -x;
	if (x < 8.0)
	return p * J1(x);
	q = Math.sqrt(2.0 / (Math.PI * x))
	* (P1(x) * (1.0 / Math.sqrt(2.0) * (Math.sin(x) - Math.cos(x))) - 8.0 / x * Q1(x)
	* (-1.0 / Math.sqrt(2.0) * (Math.sin(x) + Math.cos(x))));
	if (p < 0.0)
	q = -q;
	return q;
	}

	@Override
	public double f(final double x) {
	if (x == 0.0)
	return Math.PI / 4.0;
	return BesselOrderOne(Math.PI * x) / (2.0 * x);
	}
	}

	public static final class Blackman extends Filter {
	@Override
	public double f(final double x) {
	return 0.42 + 0.50 * Math.cos(Math.PI * x) + 0.08 * Math.cos(2.0 * Math.PI * x);
	}
	}

	public static class Box extends Filter {
	public Box() {
	super(true, .5, 1.0);
	}

	public Box(final double supp) {
	super(true, supp, 1.0);
	}

	@Override
	public double f(final double x) {
	if (x >= -0.5 && x < 0.5)
	return 1.0;
	return 0.0;
	}
	}

	public static final class Point extends Box {
	public Point() {
	super(0);
	}

	@Override
	public double fWindowed(double x) {
	// don't apply windowing as we have a radius of zero.
	return super.f(x);
	}
	}

	public static final class Catrom extends Filter {
	public Catrom() {
	super(true, 2.0, 1.0);
	}

	@Override
	public double f(double x) {
	if (x < 0)
	x = -x;
	if (x < 1.0)
	return 0.5 * (2.0 + x * x * (-5.0 + x * 3.0));
	if (x < 2.0)
	return 0.5 * (4.0 + x * (-8.0 + x * (5.0 - x)));
	return 0.0;
	}
	}

	public static final class Cubic extends Filter {
	public Cubic() {
	super(false, 2.0, 1.0);
	}

	@Override
	public double f(double x) {
	if (x < 0)
	x = -x;
	if (x < 1.0)
	return 0.5 * x * x * x - x * x + 2.0 / 3.0;
	if (x < 2.0) {
	x = 2.0 - x;
	return 1.0 / 6.0 * x * x * x;
	}
	return 0.0;
	}
	}

	public static final class Gaussian extends Filter {
	public Gaussian() {
	super(false, 1.25, 1.0);
	}

	@Override
	public double f(final double x) {
	return Math.exp(-2.0 * x * x) * Math.sqrt(2.0 / Math.PI);
	}
	}

	public static final class Hamming extends Filter {
	@Override
	public double f(final double x) {
	return 0.54 + 0.46 * Math.cos(Math.PI * x);
	}
	}

	public static final class Hanning extends Filter {
	@Override
	public double f(final double x) {
	return 0.5 + 0.5 * Math.cos(Math.PI * x);
	}
	}

	public static final class Hermite extends Filter {
	@Override
	public double f(double x) {
	if (x < 0) {
	x = -x;
	}

	if (x < 1.0) {
	return (2.0 * x - 3.0) * x * x + 1.0;
	}
	return 0.0;
	}
	}

	public static final class Lanczos extends Filter {
	public Lanczos() {
	super(true, 3.0, 1.0);
	}

	@Override
	public double f(double x) {
	if (x < 0)
	x = -x;
	if (x < 3.0)
	return (float) (sinc(x) * sinc(x / 3.0));
	return 0.0;
	}

	private double sinc(double value) {
	if (value != 0.0f) {
	value = value * Math.PI;
	return Math.sin(value) / value;
	} else {
	return 1.0;
	}
	}

	}

	public static final class Mitchell extends Filter {
	public Mitchell() {
	super(false, 2.0, 1.0);
	}

	@Override
	public double f(double x) {
	double b, c;

	b = 1.0 / 3.0;
	c = 1.0 / 3.0;
	if (x < 0)
	x = -x;
	if (x < 1.0) {
	x = (12.0 - 9.0 * b - 6.0 * c) * (x * x * x) + (-18.0 + 12.0 * b + 6.0 * c) * x * x + (6.0 - 2.0 * b);
	return x / 6.0;
	}
	if (x < 2.0) {
	x = (-1.0 * b - 6.0 * c) * (x * x * x) + (6.0 * b + 30.0 * c) * x * x + (-12.0 * b - 48.0 * c) * x
	+ (8.0 * b + 24.0 * c);
	return x / 6.0;
	}
	return 0.0;
	}
	}

	public static final class Quadratic extends Filter {
	public Quadratic() {
	super(false, 1.5, 1.0);
	}

	@Override
	public double f(double x) {
	if (x < 0)
	x = -x;
	if (x < 0.5)
	return 0.75 - x * x;
	if (x < 1.5) {
	x -= 1.5;
	return 0.5 * x * x;
	}
	return 0.0;
	}
	}

	public static final class Sinc extends Filter {
	public Sinc() {
	super(true, 4.0, 1.0);
	}

	@Override
	public double f(double x) {
	x *= Math.PI;
	if (x != 0.0)
	return Math.sin(x) / x;
	return 1.0;
	}
	}

	public static final class Triangle extends Filter {
	@Override
	public double f(double x) {
	if (x < 0.0)
	x = -x;
	if (x < 1.0)
	return 1.0 - x;
	return 0.0;
	}
	}

	/**
	* is this filter cardinal? ie, does func(x) = (x==0) for integer x?
	*/
	final boolean cardinal;

	/** radius of nonzero portion */
	double support;

	/** blur factor (1=normal) */
	double blur;

	protected Filter() {
	this(true, 1.0, 1.0);
	}

	protected Filter(final boolean cardinal, final double support, final double blur) {
	this.cardinal = cardinal;
	this.support = support;
	this.blur = blur;
	}

	public double fWindowed(double x) {
	return x < -support \|\| x > support ? 0 : f(x);
	}

	public abstract double f(double x);

	/**
	* Return the filter name.
	*
	* @return the filter's name
	*/
	public String getName() {
	return getClass().getSimpleName();
	}

	/**
	* @return the support
	*/
	public double getSupport() {
	return support;
	}

	/**
	* @param support the support to set
	*/
	public void setSupport(final double support) {
	this.support = support;
	}

	/**
	* @return the blur
	*/
	public double getBlur() {
	return blur;
	}

	/**
	* @param blur the blur to set
	*/
	public void setBlur(final double blur) {
	this.blur = blur;
	}
	}