creating buffered image

hi,
I am working on an image processing application and thought of
creating a class called FaceImage to represent a n image of a human
face.I created the class like this

public class FaceImage {
    private String fileName;
    private int width;
    private int height;
    double[] data;
        public FaceImage(File imageFile) throws MyException{
        if (isAnImageFile(imageFile.getPath())){
        try{
            BufferedImage b=ImageIO.read(imageFile);
            b=convertToGray(b);
            int w=b.getWidth();
            int h=b.getHeight();
            this.height=h;
            this.width=w;
                        this.data=new double[h*w];
            b.getData().getPixels(0,0, w,h,data);
        }catch(IOException e){
            e.printStackTrace();
        }
        }else{
            throw new MyException("file"+imageFile.getPath()+" is not an image
file");
        }
    }

       public FaceImage(String imageName,int width,int height,double[]
data) throws MyException{
        if (data.length !=width*height){
            throw new MyException("data size must be equal to "+width*height);
        }
        this.fileName=imageName;
        this.width=width;
        this.height=height;
        this.data=data;
    }
        ...

        public boolean isAnImageFile(String fileName){
               //check if an image and return true or false
               .....
        }
}

I also wanted to implement a saveImage() method so that I can save the
FaceImage object as an image file of given format.However when I tried
MemoryImageSource constructor I found that it needs an int[] not
double[].

Is there some way I can use the double[] containing pixel to save a
new image?do I need to convert the double[] to int[] as needed by
MemoryImageSource ?I guess a for loop would be very inefficient.
Any help or advice would be nice.
thanks