BorderRemoval2D.java

package edu.stanford.rsl.tutorial.atract;

import edu.stanford.rsl.conrad.data.numeric.Grid3D;
/**
 * This class implements a method to remove the borders caused by the Collimator. 
 * Use this for 2-D detectors.
 * @author Marco Boegel (Reco Project 2012 - Individual Project)
 *
 */
public class BorderRemoval2D {
	/**
	 * Use this method in combination with the Laplace2D Filter.
	 * This method searches for the collimator borders in a laplacian filtered image.
	 * The current implementation searches in each detector for the first and last non-zero element.
	 * The coordinates with the maximum number of non-zero elements across all projections are then assumed to be the 
	 * borders and set to zero.
	 * @param input Laplacian filtered Sinogram
	 */
	public void applyToGrid(Grid3D input) {
		double eps = 0.1;
		int maxProj = input.getSize()[2];
		int maxU = input.getSize()[0];
		int maxV = input.getSize()[1];
		int counter[][] = new int[maxV][maxU];
		
		for(int p = 0; p < maxProj; p++) {
			//left border
			for(int v = 0; v < maxV; v++) {
				for(int u = 0; u < maxU/2; u++){
					if(input.getAtIndex(u,v,p)*-1.0 > eps) {
						counter[v][u]++;
						break;
					}
				}
			}
			//top border
			for(int u = 0; u < maxU; u++) {
				for(int v = 0 ; v < maxV/2; v++){
					if(input.getAtIndex(u,v,p)*-1.0 > eps) {
						counter[v][u]++;
						break;
					}
				}
			}
			//right border
			for(int v = 0; v < maxV; v++){
				for(int u = maxU-1; u > maxU/2; u--){
					if(input.getAtIndex(u,v,p)*-1.0 > eps) {
						counter[v][u]++;
						break;
					}
				}
			}
			//bottom border
			for(int u = 0 ; u < maxU; u++){
				for(int v = maxV-1; v > maxV/2; v--){
					if(input.getAtIndex(u,v,p)*-1.0 > eps) {
						counter[v][u]++;
						break;
					}
				}
			}
		}
		int horizontal[] = new int[maxU];
		int vertical[] = new int[maxV];
		for(int i = 0; i < maxU; i++) {
			for(int j = 0 ; j < maxV; j++){
				horizontal[i] += counter[j][i];
				vertical[j] += counter[j][i];
			}
		}
		//left
		int tmp1  = 0;
		int max1 = 0;
		for(int i = 0; i < maxU/2; i++) {
			if(horizontal[i] > max1) {
				max1 = horizontal[i];
				tmp1 = i;
			}
		}
		//right
		int tmp2 = 0;
		int max2 = 0;
		for(int j =  maxU-1; j > maxU/2; j--) {
			if(horizontal[j] > max2) {
				max2 = horizontal[j];
				tmp2 = j;
			}
		}
		//top
		int tmp3  = 0;
		int max3 = 0;
		for(int i = 0; i < maxV/2; i++) {
			if(vertical[i] > max3) {
				max3 = vertical[i];
				tmp3 = i;
			}
		}
		//bottom
		int tmp4 = 0;
		int max4 = 0;
		for(int j =  maxV-1; j > maxV/2; j--) {
			if(vertical[j] > max4) {
				max4 = vertical[j];
				tmp4 = j;
			}
		}
		
		for(int i = 0; i < maxProj; i++) {
			for(int v = 0; v < maxV; v++){
				input.setAtIndex( tmp1,v,i, 0);
				input.setAtIndex(tmp1+1,v,i, 0);
				input.setAtIndex( tmp2,v,i, 0);
				input.setAtIndex(tmp2-1,v,i, 0);
			}
			for(int u = 0; u < maxU; u++){
				input.setAtIndex(u, tmp3, i, 0);
				input.setAtIndex(u,tmp3+1,i,0);
				input.setAtIndex(u, tmp4, i, 0);
				input.setAtIndex(u, tmp4-1, i, 0);
			}
			
		}
		
	}

	

}
/*
 * Copyright (C) 2010-2014  Marco B�gel
 * CONRAD is developed as an Open Source project under the GNU General Public License (GPL).
*/