package com.image.compare;

import java.awt.image.BufferedImage;

public class ImageComparer {
	private BufferedImage sourceImage;
	private BufferedImage candidateImage;

	public ImageComparer(BufferedImage srcImage, BufferedImage canImage) {
		this.sourceImage = srcImage;
		this.candidateImage = canImage;
	}

	/**
	 * Bhattacharyya Coefficient
	 * http://www.cse.yorku.ca/~kosta/CompVis_Notes/bhattacharyya.pdf
	 * 
	 * @return
	 */
	public double modelMatch() {
		HistogramFilter hfilter = new HistogramFilter();
		float[] sourceData = hfilter.filter(sourceImage, null);
		float[] candidateData = hfilter.filter(candidateImage, null);
		double[] mixedData = new double[sourceData.length];
		for (int i = 0; i < sourceData.length; i++) {
			mixedData[i] = Math.sqrt(sourceData[i] * candidateData[i]);
		}

		// The values of Bhattacharyya Coefficient ranges from 0 to 1,
		double similarity = 0;
		for (int i = 0; i < mixedData.length; i++) {
			similarity += mixedData[i];
		}

		// The degree of similarity
		return similarity;
	}

}