INTERACTION DESIGN PRINCIPLES FOR INTERACTIVE ...

In designing for television, going from a 4:3 aspect ratio to a 16:9 aspect ratio will
stretch the image without losing any information. However, when going from 16:9 to a
4:3 screen, the image is either cropped at the edges (center cut-out), or the entire image is
shrunk by 25%, with black bars on the top and bottom of the image (letterboxing). Figure
4.4 illustrates the difference between these two methods.
Figure 4.4 Center Cut-Out and Letterboxing
The BBC recommends that it is best to design for 4:3 because it will always
display on both standard and widescreen TV sets (2002). However, since the 16:9 aspect
ratio is the preferred format for the new HDTV standard, and since ownership of
widescreen TVs is increasing, it makes increasing sense to design interfaces for the latest
generation of televisions as well.
4.2.2 Safe Areas
Most televisions, especially older models, cut off the outer edges of the video
screen. Therefore, any media that falls outside of the “action safe” area of the screen may
be cut off. The safe areas for standard television are 10% graphics-safe and 5% action-
safe around the entire perimeter (Baker, 1999). Figures 4.5 and 4.6 illustrate the action-
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