Highlight inserts are useful for bringing out detail in specific areas that may be hard to see in one continuous colormap. There are three examples on the right showing what data may look like using these inserts. The inserts are downloadable xml files (click a colormap left of the examples) and increment by 10 percent. The top-most colormap has an insert from 0% to 10%, the next at 10% to 20%, and so on.
Here is another example, incremented by 20% instead of 10%