Positive and Negative text over background

Ever wonder about what is the fastest way to create that positive / negative text over backgrounds? The following is kind of obvious and kind of not.

The solution is around layer Blend modes. Try this:
  1. Design your background layer
  2. Add a second layer for your text
  3. Try different Blend modes of the text layer
By optioning through the blend modes see some mixed results, some good and some not.

Now, Step 4 is to apply the same color to both, the Text AND the Background elements, and select the blend mode Difference.

This forces the overlapping parts to be black (the difference of one RGB color and the same RGB color is zero, or black), while the non-overlapping elements remain the selected color.

Here is a screen shot for re:

Further reading: wikipedia.org/wiki/Blend_modes