chromasens allPIXA, Руководство пользователя

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CD40047_R04_allPIXA_User-Manual.docx 144
Stop gain control
if level < ‘Stop gain control’ * last gain value
If the value of the white reference video level is lower than the specified value
of
Gain control stop factor , the closed-loop control for the white balancing
could be paused by using this option (for example if the light on the white
reference is lowered without any present document (stray-light from the
document).
Stop gain control by variance value
If the medium variance of the white reference video level is higher than the
specified value of
Set gain control stop by variance , the closed-loop control
for the white balancing could be paused by using this option. For experienced
users only.
Gain control stop factor
Name
Name
Gain control stop factor
Function
Sets the pause condition for the white control.
Channels All
Unit Float Step: 1/1024
Dependency
It is only available if the check boxes Enable continuous white control and Stop
gain control are both selected in the White control area.
Notes
If you use this condition, the white control pauses:
Average of all actual “Current white reference values” < value * Average of the last
valid “Current white reference values”.
Camera: Value CST:
Lower limit All
0
Upper limit All 1,00
1. Description of paper (object) detection function:
During the scan, the camera is set to automatically control the image brightness using the
implemented function “Automatic white control”. The control mechanism of the camera uses
the reference area on the object to adapt the camera gain values as defined within the
camera parameters.
In certain situations during the scan process it can occur that an object is missing on the
transport. If no object is on the transport, the reference area for the brightness control
appears darker than the normal paper white. Therefore, a missing object can irritate and
misguide the automatic gain process. With the paper detection functionality, the existence
of a sheet is detected and the automatic gain control stops if no object (certain degree of
brightness) is found on the transport.
2. Basic functionality description:
The camera reads the white value of the reference area. If the brightness of the reference
area is below the suppress condition, automatic white control is disabled only for the
currently scanned image. The procedure is applied separately to each acquired image.
3. Suppress condition:
Mean of value of actual reference area < (mean value of desired values of all channels *
threshold factor).
4. Feedback camera signal:
While gain control is disabled, the image is scanned with the last valid gain values. The
camera sets a flag if the values in the reference area are too low (-> no paper) and the
“automatic gain control” function is disabled.