// Catalano Imaging Library
// The Catalano Framework
//
// Copyright © Diego Catalano, 2012-2016
// diego.catalano at live.com
//
//    This library is free software; you can redistribute it and/or
//    modify it under the terms of the GNU Lesser General Public
//    License as published by the Free Software Foundation; either
//    version 2.1 of the License, or (at your option) any later version.
//
//    This library is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
//    Lesser General Public License for more details.
//
//    You should have received a copy of the GNU Lesser General Public
//    License along with this library; if not, write to the Free Software
//    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
//

package Catalano.Imaging.Filters;

import Catalano.Imaging.FastBitmap;
import Catalano.Imaging.IApplyInPlace;

/**
 * Remove artifacts caused by uneven lightning.
 * 
Actually this technique is useful as a preprocessing step for all texture measures.
 * 
Reference: Computer Imaging: digital image analysis and processing / Scott E. Umbaugh. Chapter 6. p. 276
 * 
 * 
Properties:
 * 
Supported types: Grayscale.
 * 
Coordinate System: Matrix.

 * 
 * @author Diego Catalano
 */
public class ArtifactsRemoval implements IApplyInPlace{
    
    private int windowSize = 15;

    /**
     * Initialize a new instance of the ArtifactsRemoval class.
     */
    public ArtifactsRemoval() {}

    /**
     * Initialize a new instance of the ArtifactsRemoval class.
     * @param windowSize Window size.
     */
    public ArtifactsRemoval(int windowSize) {
        this.windowSize = windowSize;
    }

    @Override
    public void applyInPlace(FastBitmap fastBitmap) {
        
        if (fastBitmap.isGrayscale()){
            FastBitmap copy = new FastBitmap(fastBitmap);
            int width = fastBitmap.getWidth();
            int height = fastBitmap.getHeight();
            int steps = windowSize / 2;

            for (int x = 0; x < height; x++) {
                for (int y = 0; y < width; y++) {

                    double sum = 0;
                    int hits = 0;
                    for (int i = x - steps; i < x + steps; i++) {
                        for (int j = y - steps; j < y + steps; j++) {

                            if (((i >= 0) && (j >= 0)) && ((i < height) && (j < width))){
                                sum += copy.getGray(i, j);
                                hits++;
                            }
                        }
                    }
                    double mean = sum / hits;
                    fastBitmap.setGray(x, y, (int)(fastBitmap.getGray(x, y) - mean));
                }
            }
        }
        else{
            throw new IllegalArgumentException("Artifacts Removal only works in grayscale images.");
        }
    }
}