-the one technique that EVERYONE should learn-
The highlight effect is arguably the single most useful technique in communicating with digital media. It is the one digital effect that everyone who presents with Powerpoint or Keynote should know. For this reason: highlighting is the surest way to focus the attention of viewers.
Applied to a text, the effect looks like this:
The effect also works well on images, directing the gaze to details that might easily pass unnoticed.
The special power of this technique owes to two features:
The first is change: the attention of viewers is immediately heightened when change occurs (the recommended transition time: 1.5-2 seconds).
The second is the reduction of distractions. At the same time that it draws the eye to one part of a slide, highlighting diminishes the visibility of other parts. Look at how much more effectively it concentrates the gaze than other common techniques such as underlining or pointing arrows:
Such effects are easy to create in Keynote and Powerpoint. The secret lies in an extraordinarily useful technique called masking. If you are unfamiliar with what masking is, or don’t know how to create mask images in Keynote/Powerpoint, you should learn here, before going further.
Highlighting in Keynote
The highlight effect can be achieved in Keynote in two ways. The results are identical, and both turn on a clever application of masking.
To achieve the best results, first set the background of the slides to black. This will create the sharpest contrasts in brightness, and thus the clearest highlights.
Method 1: Dynamic change within a single slide
- Duplicate the slide containing the image
- Mask the image on the duplicate slide, so that only the part that you want to highlight remains. (For slightly more detail on this step see “Masking with Shapes” on this page)
- Copy that part back onto the first slide. The first slide thus now has a copied partial image lying on top of the original complete image
- Click the original complete image to select it, and go to Animate => Action => Opacity, and set Duration to 1.5-2 seconds, and Opacity to 33-38% (these settings can of course be adjusted according to your preference)
- Now, when you Play the presentation, and hit the Space bar, the background image will dim gradually, leaving only the masked portion highlighted.
- Optional: if you want to restore the original full image, selected the image again, then go to Animate => Action => Add Action => Opacity, then set Opacity to 100%
Method 2: Highlighting appears in transition between slides
- Make TWO COPIES of the original slide
- Mask the image on the THIRD slide, so that only the part that you want to highlight remains. (For slightly more detail on this part see “Masking with Shapes” on this page)
- Copy that part back onto the SECOND slide. This slide thus now has a copied partial image lying on top of the original complete image.
- Select the background complete image and set its opacity to 33-38%
- Delete the third slide.
- Click on the first slide to select it, then go to: Animate => Add an Effect => Dissolve, setting Dissolve to 1.5-2 secs.
- Now, when you Play the presentation, and hit the spacebar, the background image will gradually dim leaving only the masked portion highlighted.
- Optional: if you want to restore the original full image, add a copy of the first slide and place it after the second slide. Select the second slide, then go to: Animate => Add an Effect => Dissolve, setting Dissolve to 1.5-2 secs.
Highlighting in Powerpoint
One Step Further: the Shifting Spotlight
Once you know how to highlight one section of an image, it is a simple matter to create a shifting spotlight like this:
Here two masked images lie on top of the complete original. As the opacity of the original is reduced, the image on the left appears highlighted. The impression of a spotlight shift is created by dissolving it out at the same time that the right image is dissolved in.
Dissecting Vesalius: an Example of Using Shifting Highlights to Analyze an Image
Vesalius’s anatomical treatise known as the Fabrica (1543) has often been celebrated as one of the landmarks in the rise of modern science. Against the medieval anatomy professors who had been content merely to intone the teachings found in the works of Galen, Vesalius, we are told, insisted on the importance of directly observing the human body. The frontispiece to the Fabrica is thus one of the most famous illustrations in the history of medicine. But it is a very crowded and complex scene. The highlight effect allows us to dissect the various groups in the picture, and discover that this book, which reputedly touts the primacy of observation opens, intriguingly, with a scene of distraction (with so many viewers fixing on things other than the dissected corpse). Moreover, the one critical element on which the dissector insists with his pointed finger–the figure, indeed, occupying the very center of the scene–is, revealingly, the skeleton that all the surrounding onlookers fail to see.
The basic technique for these shifting highlights is the same as that described above, but cutting out complex shapes such as those in this frontispiece requires more powerful masking tools than those available in Keynote or Powerpoint. The masks for this example were all created in Photoshop.
Creating a True Spotlight
Those with access to the screen recording program Camtasia can use it to create highlights that resemble true spotlights:
The page on leveraging screen recording contains a quick tutorial on how to compose this effect in Camtasia.