How to improve and not get OutOfMemory?

Hello!

I use to get outof memory on 2 methods looking like:
    public void snapImageFile(String filename)
    {
        BufferedImage bImage = doRender(dim.width, dim.height);
        try
        {
            FileOutputStream fos = new FileOutputStream(filename+"." + imageType);
            BufferedOutputStream bos = new BufferedOutputStream(fos);

            ImageIO.write(bImage,imageType,bos);

            bos.flush();
            fos.close();
        }
        catch (Exception e)
        {
            System.out.println(e);
        }
    }

    public void writeImage(OutputStream outputStream)
    {
        BufferedImage bImage = doRender(dim.width, dim.height);
        try
        {
            BufferedOutputStream bos = new BufferedOutputStream(outputStream);

            ImageIO.write(bImage,imageType,bos);
            bos.flush();
        }
        catch (Exception e)
        {
            System.out.println(e);
        }
    }
Do you guys got any ideeas how to improve them?

Best reagrsd
Fredrik