public Double getValue(GriddedTile griddedTile, WritableRaster raster,
			int x, int y) {
		short pixelValue = getPixelValue(raster, x, y);
		Double value = getValue(griddedTile, pixelValue);
		return value;
	}
public Double getValue ( GriddedTile griddedTile , WritableRaster raster , int x , int y ) { short pixelValue = getPixelValue ( raster , x , y ) ; Double value = getValue ( griddedTile , pixelValue ) ; return value ; }
Get the coverage data value

@param griddedTile
gridded tile
@param raster
image raster
@param x
x coordinate
@param y
y coordinate
@return coverage data value