vifix.cn

package cn.vifix.uilab;
 
import java.awt.image.ConvolveOp;
import java.awt.image.Kernel;
 
public class GaussianBlurFilter
{
	public static ConvolveOp getGaussianBlurFilter(int radius, boolean horizontal){
		if (radius < 1){
			throw new IllegalArgumentException("Radius must be >= 1");
		}
 
		int size = radius * 2 + 1;
		float[] data = new float[size];
 
		float sigma = radius / 3.0f;
		float twoSigmaSquare = 2.0f * sigma * sigma;
		float sigmaRoot = (float) Math.sqrt(twoSigmaSquare * Math.PI);
		float total = 0.0f;
 
		for(int i = -radius; i <= radius; i++){
			float distance = i * i;
			int index = i + radius;
			data[index] = (float) Math.exp(-distance/twoSigmaSquare) / sigmaRoot;
			total += data[index];
		}
 
		for(int i = 0; i < data.length; i++){
			data[i] /= total;
		}
 
		Kernel kernel = null;
		if(horizontal){
			kernel = new Kernel(size,1,data);
		}
		else{
			kernel = new Kernel(1,size,data);
		}
 
		return new ConvolveOp(kernel, ConvolveOp.EDGE_NO_OP, null);
	}
 
	private GaussianBlurFilter(){}
}