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9
Functions
DFW-SX910/X710
Gamma
Used for setting gamma compensation to OFF, ON (1),
or ON (2).
OFF : Outputs CCD signals for image processing
linearly.
ON (1) : For obtaining natural gradation taking into
account the characteristics of the monitor.
ON (2) : For obtaining three-dimensional images with
a subject that has a small luminance dynamic
range.
Concept of Gamma Characteristics
Shutter
This feature sets exposure time. Both manual and
automatic settings are available.
When the automatic setting is selected, Shutter is
adjusted automatically, based on the brightness of the
subject.
At this time, the reference level (target point) of the
brightness is set in the Auto Exposure register.
With manual setting, the camera uses relative control
values indicated by a 12-bit integer and absolute
control values indicated using a 32-bit floating point
number.
Relative control values for Shutter
The relationship between the parameter and the
exposure time is given by the following formulas.
Where
P = Parameter (003h ~ 47Eh)
E = Exposure time (s)
P >= 3 ~ P <= 1000
P
2
E = + 0.000005
1000000
P > 1000 ~ P <= 1150
E = (P – 1000)
*
0.1 + 1.000005
Input
Output
Gamma ON (2)
Gamma ON (1)
Gamma OFF
Setting examples
3 (003h) : 14
µ
s (1/100000)
32 (020h) : 1.005 ms (1/1000)
100 (064h) : 10.005 ms (1/100)
1000 (3E8h) : 1 s
1010 (3F2h) : 2 s
1150 (47Eh) : 16 s
For details on Auto Exposure, see page 8.
For long exposure times
When exposure times longer than the currently set
frame rate cycle are set, the camera enters the long
exposure time mode, and the actual frame rate is
slowed in accordance with the exposure time.
Absolute control values for Shutter
Control of exposure time using absolute values is
possible. The values are indicated using a 32-bit
floating point value. (Unit: sec.)
The control steps are synchronized with the pixel
clock, and as the pixel clock is 15.25 MHz, one step is
approximately 65.6 ns.
The range for these values extends from
10 microseconds to 17.5 seconds.
Programming example;
union {
DWORD dwValue; // 1394 is expressed in quadlets,
float fValue; //
exposure time is indicated in seconds.
} AbsoluteShutterValue;
AbsoluteShutterValue.fValue = Exposure time;
WriteQuad(AbsoluteShutterOffsetAddress,
AbsoluteShutterValue.dwValue);
WriteQuad is a virtual function used to write in the
1394 register.
16 s
1 s
10 µs
3 1000
1
2
1150
1
2