I came across the same problem, and I have fixed it in my client today. The bug is in Java's ImageIO thingy. I replaced the calls to ImageIO.read with javapng (http://code.google.com/p/javapng/), and grayscale images render properly now. This is a very simple change and it shouldn't take much time for Mojang to implement.
Andrew Harrison
I came across the same problem, and I have fixed it in my client today. The bug is in Java's ImageIO thingy. I replaced the calls to ImageIO.read with javapng (http://code.google.com/p/javapng/), and grayscale images render properly now. This is a very simple change and it shouldn't take much time for Mojang to implement.