title: Add color to a grayscale BufferedImage
body: <p>Can't find an answer to this, maybe its too basic. I have a gray scale <code>BufferedImage</code> (basically a section from a black-and-white PDF), and I'd like to draw a red box on the image. However, when I do so and save the image, the red box comes out as grey.</p>
  
  <p>How to correctly add color to a gray scale <code>BufferedImage</code>?</p>
  
  <p>I suppose I need to convert the color model(?) from gray scale to RGB? Although I don't need to convert the black and white parts of the image to color - that is to say the resulting image can be black and white.  So long as I can draw a red line on the image without it saving as a shade of gray.</p>
  
  <p>The image file is a GIF. </p>