The rule is displayed at the top. Since there are three colours (red, green and blue), there are 27 combinations (red, red, red; red, red, green; red, red, blue; etc).
The panel on the right displays the generated pattern, while the panel on the left shows a close up.
By picking any pixel in the left panel and examining the three pixels above it, it can be seen from the rule how the pixel's colour is determined.
When New Rule is clicked, the program randomly assigns new colours to each of the 27 colour combinations, randomly chooses a background colour (every pixel is initially set to this colour) and randomly chooses a different colour for the top row's central pixel (ie: if the background is green, the central pixel will be either red or blue).
Then the program steps through the iterations of colouring each row by examining the row above.
The user can at anytime pause this process by clicking Pause, or start the process again by clicking New Rule.
If Automatic New Rule is selected, when the right panel is completely filled, the program starts again with a new rule. I