Canon Camera, Hackers Manual

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2.3 The CHDK: What it is and how it works
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display of zebra areas (over- and underexposed image areas masked with a
zebra pattern) that allow you to judge exposure before shooting. These in-
formation items can be arranged freely on the screen with the help of the
built-in OSD editor.
The Edge Overlay feature is also very useful. When switched on, the
contours of a shot are extracted and appear as an overlay on the display.
This allows you to align the following shots to the overlay, and thus to the
previous shot. This is particularly useful when shooting panoramas, for
bracketing work such as HDR photography or focus stacking, or for shoot-
ing 3D stereo images with a single camera. Unfortunately, this feature does
not work in video mode where it could be useful for connecting different
takes.
Remote control
While Canon EOS cameras allow full remote control, there are no provi-
sions of that kind for most compact cameras. Again, the CHDK adds that
feature to supported compact cameras and enables
remote control
through the camera’s USB port—including shutter release, zooming, and
the possibility of remote functionality in scripts.
Utilities and games
Finally, the CHDK comes with a number of useful utilities such as a file
browser, which allows you to browse the memory card’s file system and to
delete files and folders. There is also a calendar and a text file reader (for
example, to read script documentation), and finally, a number of games in
case you get bored.
Figure 2-3
An incentive to always take your
camera with you: games in the
camera’s display (here, Reversi). A
battery indicator keeps you informed
about the remaining power for
shooting.