Digital Light & Color

Using Text Drop Shadow with Offset=0, Transparency=0 and Softness>0, while the font colour is set to black and the shadow to white (or vice versa), can be useful to write text which will be universally readable on dark and light backgrounds.

Good tip, Maciej. I have sometimes used a text mask with an inverted brightness curve (usually a stair step with 50% crossover) to achieve readability on images having variable background brightness, but this might work better.

Thanks to both of you - I've often wondered what to do for a better result in those circumstances.
Mike.