Allied Vision Technologies MF-145B2 Instruction Manual download pdf (Page 50)

Description of the data path

MARLIN Technical Manual

Page 42

For further tuning, readjust KNEEPOINT_X but maintain ratio KNEEPOINT_1 > KNEEPOINT_2 >

KNEEPOINT_3

8.3 White balance

The color cameras have both manual and automatic white balance and can be set via the analog

red and blue gain in the 0...+12 dB range. White balance is used so that non-colored image parts

are displayed non-colored.

These settings are made in register 80Ch 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.

8.3.1 Automatic white balance

Automatic white balance is activated by setting the “One Push” bit in the WHITE_BALANCE

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 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 this process is aborted.

The following flow diagram illustrates the automatic white balance sequence.

1 2 ... 45 46 47 48 49 50 51 52 53 54 55 ... 130 131

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Allied Vision Technologies MF-145B2 Instruction Manual Page 50