Canon Digital IXUS 75 Advanced User's Manual page 59

You are recommended to set the shooting mode to
and the exposure compensation setting to [±0]
before setting a custom white balance.
The correct white balance may not be obtained when
the exposure setting is incorrect (image appears
completely black or white).
Shoot with the same settings as when reading the
white balance data. If the settings differ, the optimal
white balance may not be set.
In particular, the following should not be changed.
- ISO Speed
- Flash
Setting the flash to on or off is recommended. If the
flash fires when reading the white balance data with
the flash set to
use the flash when you shoot.
Since the white balance data cannot be read in Stitch
Assist mode, preset the white balance in another
shooting mode beforehand.
If you register the
function with the
balance data each time you press the
(Auto), make sure that you also
(Custom White Balance)
button (p. 67), obtain the white
button.
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