For that, you'll just have to make a colormap image and a bumpmap image. The
colormap gives the color of the pixels and the bumpmap gives the altitude.
The brighter, the higher. Then, the applet calculates the horizontal and
vertical slope of every pixel by using the altitudes of the surrounding
pixels. This means that the bumpmap image should be 1 rim of pixels bigger on
every side, which makes it 2 pixels wider and higher than the colormap image.
The applet itself is twice the width and height of the colormap image. The
colormap image may contain up to 256 colors and the bumpmap should be
grayscale.
