You can still make interesting images from those types, though, so don't avoid them. Some folks like the effect. Generally this should be set to one less than the number of colors, i.e. usually 255. If it is too high, the range of colors in the picture will be much less than those available. There is no easy way to predict in advance what this value should be.
Larger values give more accurate and smoother potential.
A value of 500 gives excellent results. This is because even with 256 colors, the continuous potential is being truncated to integers. If you happen to view the saved image with a GIF viewer other than Fractint, you'll find that it is twice as wide as it is supposed to be. You might find with 16bit continuous potential that there's a long delay at the start of an image, and disk activity during calculation. Back to The Fractint Home Page.