// get a reader
        final MrSIDReader reader = new MrSIDReader(file);
        
        //
        // read once
        //
        GridCoverage2D gc = (GridCoverage2D) reader.read(null);

        //
        // read again with subsampling and crop
        //
        final int originalW = gc.getRenderedImage().getWidth();
        final int originalH = gc.getRenderedImage().getHeight();
        final Rectangle range = ((GridEnvelope2D)reader.getOriginalGridRange());
        final GeneralEnvelope originalEnvelope = reader.getOriginalEnvelope();
        final GeneralEnvelope reducedEnvelope = new GeneralEnvelope(new double[] {
                originalEnvelope.getLowerCorner().getOrdinate(0),
                originalEnvelope.getLowerCorner().getOrdinate(1)},
                new double[] { originalEnvelope.getMedian().getOrdinate(0),
                        originalEnvelope.getMedian().getOrdinate(1)});
        reducedEnvelope.setCoordinateReferenceSystem(reader.getCrs());

        final ParameterValue gg = (ParameterValue) ((AbstractGridFormat) reader
                .getFormat()).READ_GRIDGEOMETRY2D.createValue();
        gg.setValue(new GridGeometry2D(new GridEnvelope2D(new Rectangle(0, 0,
                (int) (range.width / 2.0),
                (int) (range.height / 2.0))), reducedEnvelope));
        gc = (GridCoverage2D) reader.read(new GeneralParameterValue[] { gg });
        Assert.assertNotNull(gc);
        // NOTE: in some cases might be too restrictive
        Assert.assertTrue(reducedEnvelope.equals(gc.getEnvelope(), XAffineTransform
                .getScale(((AffineTransform) ((GridGeometry2D) gc
                        .getGridGeometry()).getGridToCRS2D())) / 2, true));
        // this should be fine since we give 1 pixel tolerance
        Assert.assertEquals(originalW / 2.0 , gc.getRenderedImage()
                .getWidth(), 1);
        Assert.assertEquals(originalH / 2.0 , gc.getRenderedImage()
                .getHeight(), 1);

        forceDataLoading(gc);

        // /////////////////////////////////////////////////////////////////////
        //
        // Read ignoring overviews with subsampling and crop, using Jai,
        // multithreading and customized tilesize
        //
        // /////////////////////////////////////////////////////////////////////
        final ParameterValue policy = (ParameterValue) ((AbstractGridFormat) reader
                .getFormat()).OVERVIEW_POLICY.createValue();
        policy.setValue(OverviewPolicy.IGNORE);
        
        // //
        //
        // Enable multithreading read
        //
        // //
        final ParameterValue mt = (ParameterValue) ((BaseGDALGridFormat) reader
                .getFormat()).USE_MULTITHREADING.createValue();
        mt.setValue(true);
        
        // //
        //
        // Customizing Tile Size
        //
        // //
        final ParameterValue tilesize = (ParameterValue) ((BaseGDALGridFormat) reader
                .getFormat()).SUGGESTED_TILE_SIZE.createValue();
        tilesize.setValue("512,512");
        
        // //
        //
        // Setting read type: use JAI ImageRead 
        //
        // //
        final ParameterValue useJaiRead = (ParameterValue) ((BaseGDALGridFormat) reader
                .getFormat()).USE_JAI_IMAGEREAD.createValue();
        useJaiRead.setValue(true);
        gc = (GridCoverage2D) reader.read(new GeneralParameterValue[] { gg,
                policy, mt, tilesize, useJaiRead });