code: public void Write(OutputStream output) throws IOException {
  	BitUtils.WriteString(output, "GIF87a");
  	
  	ScreenDescriptor sd = new ScreenDescriptor(width_, height_,
  						   numColors_);
  	sd.Write(output);
  
  	output.write(colors_, 0, colors_.length);
  
  	ImageDescriptor id = new ImageDescriptor(width_, height_, ',');
  	id.Write(output);
  
  	byte codesize = BitUtils.BitsNeeded(numColors_);
  	if (codesize == 1)
  	    ++codesize;
  	output.write(codesize);
  
  	LZWCompressor.LZWCompress(output, codesize, pixels_);
  	output.write(0);
  
  	id = new ImageDescriptor((byte)0, (byte)0, ';');
  	id.Write(output);
  	output.flush();
      }
docs: Writes the image out to a stream in the GIF file format. This will
  be a single GIF87a image, non-interlaced, with no background color.
  <B>This may take some time.</B><P>
  
  @param output The stream to output to. This should probably be a
  buffered stream.
  
  @exception IOException Will be thrown if a write operation fails.