/**
 * @author Pacien TRAN-GIRARD
 * @author Timothée FLOURE
 */
public final class Filter {

    /**
     * Get a pixel without accessing out of bounds
     *
     * @param gray a HxW float array
     * @param row  Y coordinate
     * @param col  X coordinate
     * @return nearest valid pixel color
     */
    public static float at(float[][] gray, int row, int col) {
        int maxRow = gray.length - 1;
        int maxCol = gray[0].length - 1;

        if (row < 0) row = 0;
        if (col < 0) col = 0;

        if (row > maxRow) row = maxRow;
        if (col > maxCol) col = maxCol;

        return gray[row][col];
    }

    /**
     * Convolve a single-channel image with specified kernel.
     *
     * @param gray   a HxW float array
     * @param kernel a MxN float array, with M and N odd
     * @return a HxW float array
     */
    public static float[][] filter(float[][] gray, float[][] kernel) {
        // TODO filter
        return null;
    }

    /**
     * Smooth a single-channel image
     *
     * @param gray a HxW float array
     * @return a HxW float array
     */
    public static float[][] smooth(float[][] gray) {
        // TODO smooth
        return null;
    }

    /**
     * Compute horizontal Sobel filter
     *
     * @param gray a HxW float array
     * @return a HxW float array
     */
    public static float[][] sobelX(float[][] gray) {
        // TODO sobelX
        return null;
    }

    /**
     * Compute vertical Sobel filter
     *
     * @param gray a HxW float array
     * @return a HxW float array
     */
    public static float[][] sobelY(float[][] gray) {
        // TODO sobelY
        return null;
    }

    /**
     * Compute the magnitude of combined Sobel filters
     *
     * @param gray a HxW float array
     * @return a HxW float array
     */
    public static float[][] sobel(float[][] gray) {
        // TODO sobel
        return null;
    }

}