Can I fade the slide background image?
I would like to fade the background image in my slides, so the words can be read easier. How do I do that?
OS X Mavericks (10.9), Keynote 6.0.1
The easiest way to achieve this is to overlay a box to cover the background image - it can be opaque or semi-transparent, black or white. Build it in just a tiny bit ahead of your text and make sure your text 'pops' out from that background.
I frequently use a semi-transparent black box - no stroke, no shadow - adjusting the opacity to achieve the degree of 'blurring' I want for the background image. I build in the box with an 'on click' animation, usually 'dissolve' of about 0.70 seconds. I then build in my text as a 'with previous' dissolve and set the delay to half the duration of the box's build. That way nothing jars on the eye.
When I use a semi-transparent black box, I typically use white lettering, usually with a very fine shadow - 2 point offset, 1 point blur - to make it stand proud of the box behind it. You can highlight a word with bright red or golden-yellow text here and there, but keep those bright colours for special occasions, don't overdo them.
Once you've done this once, simply copy the slide, change the background image as needed and off you go, re-typing your text for each copy you make.
You can achieve this by messing around with an overlay on a newly-defined master too, but that restricts you in the transitions you can use to achieve the fading effect for the background image. This way is clean and simple. Have fun.