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7.2
White balance
The color cameras have both manual and automatic white balance, that can be set via
the analog red and blue gain in the 0...+10 dB range. White balance is used so that non
colored image parts are displayed non colored.
These settings are made in register 80C of IIDC v. 1.3. The values in the
V_Value/R_Value
field produce changes in the gain from green to red and in the
U_Value/B_Value
field from green to blue.
Values in the 0...53 range may be entered.
7.2.1
Automatic white balance
Automatic white balance is activated by setting the “One Push” bit in the
WHITE_BALANCE register (see
WHITE-BALANCE
). The camera independently inputs frames
and calculates the U/B and V/R correction values on the basis of 16x16 pixels from the
center of the currently set frame.
For white balance incoming frames are input based on the current settings of all
registers (GAIN, OFFSET, SHUTTER, etc.).
The following ancillary conditions should be observed for successful white balance:
All pixels in the 16x16 calculation window must have a gray value <255 and the
object in the calculation window must be monochrome.
Automatic white balance can be started both during active image capture and also
when the camera is in idle state.
If the image capture is active (e.g. “IsoEnable” set in register 614h), the frames used
by the camera for white balance are also output on the 1394 bus. Any previously active
image capture is started again after the completion of white balance.
Automatic white balance can also be started by using an external trigger. However, if
there is a pause of >10 seconds between capturing individual frames the process is
aborted.