User manual

Small Vision System User Manual 48
If max_decimation is 1, then the stereo cameras don’t support explicit decimation. A
value of 2 means the cameras can decimate by 2 horizontally and vertically, and a value of 4
means they can decimate by 2 or 4. For example, the MEGA-D has a decimation value of 4,
which means that it supports image sizes of 1288 x 960, 640 x 480, and 320 x 240. Note
that most analog framegrabbers support implicit subsampling, by setting the frame size.
These functions are used by digital cameras like the MEGA-D that support subsampling at
the imager.
If max_binning is 1, then the stereo cameras don’t support explicit binning. Binning is
like decimation, but it averages a group of pixels. A value of 2 means the cameras can
decimate by 2, and a value of 4 means they can decimate by 2 or 4. These functions are used
by digital camera that support subsampling at the imager. For the MEGA-D, the interface
library supports software binning by a factor of 2.
int decimation
int binning
These are the current values for decimation and binning. They should be set before calling
svsVideoStartContinuous.
int color
This parameter controls whether or not color information is made available. If it is 0, no
color information is returned to the user program from svsVideoGetImage. If it is 1,
and the stereo head has color capability, a color image is returned.
5.2.6 Digitization Parameters
Some framegrabbers and cameras support control over the appearance of an image, the relationship
between light reaching the sensor and the pixel value produced. Most cameras have automatic exposure
and gain control; the framegrabber can set brightness and contrast as it digitizes the analog signal. The
MEGA-D has manual exposure and gain.
In general, the digitization parameters can be changed at any point, even when the video is streaming
to the user program. The special function svsVideoSetDigParams will immediately apply all
digitization settings that have changed since the start of video streaming, or the last call to
svsVideoSetDigParams.
int svsVideoSetDigParams(svsSP *sp)
Checks the digitization parameters in sp, and if any of them have changed since the last call
to this function or to svsVideoStartContinuous, it updates them on the stereo
hardware. Returns 0 if the call succeeds, -1 if not.
int autogain
int manualgain
int autowhite
int manualwhite
These parameters give information about the digitization modes available from the cameras.
They are set by the interface software when the cameras are opened with svsVideoOpen,
and should not be changed by the user.
If autogain is 1, the cameras can set gain and exposure automatically to compensate for
changing lighting conditions. If manualgain is 1, the user can set exposure and gain
under program control. These are not necessarily exclusive: some cameras support both auto