public class Test {
    public static void test(java.io.File file) throws Exception {
        ParameterValue<OverviewPolicy> policy = AbstractGridFormat.OVERVIEW_POLICY.createValue();
        policy.setValue(OverviewPolicy.IGNORE);
        //this will basically read 4 tiles worth of data at once from the disk...
        ParameterValue<String> gridsize = AbstractGridFormat.SUGGESTED_TILE_SIZE.createValue();
        //Setting read type: use JAI ImageRead (true) or ImageReaders read methods (false)
        ParameterValue<Boolean> useJaiRead = AbstractGridFormat.USE_JAI_IMAGEREAD.createValue();
        useJaiRead.setValue(true);
        GridCoverage2DReader reader = new GeoTiffReader(file);
        GridEnvelope dimensions = reader.getOriginalGridRange();
        GridCoordinates maxDimensions = dimensions.getHigh();
        int w = maxDimensions.getCoordinateValue(0)+1;
        int h = maxDimensions.getCoordinateValue(1)+1;
        int numBands = reader.getGridCoverageCount();
        GridCoverage2D coverage = reader.read(
            new GeneralParameterValue[]{policy, gridsize, useJaiRead}
        );
        GridGeometry2D geometry = coverage.getGridGeometry();
        for (int i=0; i<w; i++) {
            for (int j=0; j<h; j++) {
                org.geotools.geometry.Envelope2D pixelEnvelop =
                geometry.gridToWorld(new GridEnvelope2D(i, j, 1, 1));
                double lat = pixelEnvelop.getCenterY();
                double lon = pixelEnvelop.getCenterX();
              
                double[] vals = new double[numBands];
                coverage.evaluate(new GridCoordinates2D(i, j), vals);
                //Do something!
            }
        }
    }
}

public class GeoTIFFTest {
    private final static String url = "jdbc:postgresql://localhost/bag";
    private static GridCoverage2D grid;
    private static Raster gridData; // java.awt.image.Raster;
 
    public static void main(String[] args) throws Exception {
        initTif();
        loadData();
    }
 
    private static void initTif() throws Exception {
        File tiffFile = new File("/Volumes/Iomega_HDD/mac/data/r44hn1.tif");
        GeoTiffReader reader = new GeoTiffReader(tiffFile);
        grid =reader.read(null);
        gridData = grid.getRenderedImage().getData();
    }
 
    private static double getValue(double x, double y) throws Exception {
        GridGeometry2D gg = grid.getGridGeometry();
        DirectPosition2D posWorld = new DirectPosition2D(x,y);
        GridCoordinates2D posGrid = gg.worldToGrid(posWorld);
 
        // envelope is the size in the target projection
        double[] pixel=new double[1];
        double[] data = gridData.getPixel(posGrid.x, posGrid.y, pixel);
        return data[0];
    }
 
    private static void loadData() throws Exception {
        Connection conn = DriverManager.getConnection(url);
        QueryRunner runner = new QueryRunner(); // org.apache.commons.dbutils.QueryRunner;
        final Map<Long, Double> map = new HashMap<Long, Double>();
        ResultSetHandler handler = new ResultSetHandler() {
 
            @Override
            public Object handle(ResultSet resultSet) throws SQLException {
                while (resultSet.next()) {
                    String point = resultSet.getString("point");
                    double x = Double.parseDouble(point.substring(
                            point.indexOf('(') + 1,
                            point.indexOf(' ')
                    ));
 
                    double y = Double.parseDouble(point.substring(
                            point.indexOf(' ') + 1,
                            point.indexOf(')')
                    ));
 
                    try {
                        double hoogte = getValue(x, y);
                        map.put(resultSet.getLong("gid"),hoogte);
                    } catch (Exception e) {
                        e.printStackTrace();  
                    }
                }
                return null;  
            }
        };
        runner.query(conn, "SELECT gid, ST_AsText(ST_Centroid(geovlak)) as point \n" +
                "FROM bag8mrt2014.pand\n" +
                "WHERE geovlak && ST_MakeEnvelope(130153, 408769,132896, 410774, 28992) ORDER by gid ;", handler);
        int count = 0;
        for (Long key : map.keySet()) {
            System.out.println("Inserting for key = " + key + " value: " + map.get(key));
            int col = runner.update(conn, "UPDATE bag8mrt2014.pand SET hoogte= ? where gid = ?",
            map.get(key), key);
            count++;
            if (count%100 == 0) {
                System.out.println("count = " + count);
            }
        }
    }
}