package ie.dcu.image.gray;

import ie.dcu.matrix.DoubleMatrix;

public class GrayConvolve {

	public static DoubleMatrix convolve(
			DoubleMatrix image, DoubleMatrix filter) 
	{
		DoubleMatrix result = new DoubleMatrix(image.rows, image.cols);
		
		for (int i = 0; i < image.rows; i++) {
			for (int j = 0; j < image.cols; j++) {
				double value  = 0.0;
				
				for (int ii = 0; ii < filter.rows; ii++) {
					int i1 = i - (filter.rows >> 1) + ii;
					
					if (image.hasRow(i1)) {
						for (int jj = 0; jj < filter.cols; jj++) {
							int j1 = j - (filter.cols >> 1) + jj;
							
							if (image.hasCol(j1)) {
								double filterValue = filter.doubleAt(ii, jj);
								value += image.doubleAt(i1, j1) * filterValue;
							}
						}
					}
				}
				
				result.setDoubleAt(i, j, value);
			}
		}
		
		return result;
	}
}