User`s manual

DCSG USER’S MANUAL ©2007 VIDERE DESIGN
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transferred on the IEEE 1394 bus, then binned down. The binning is color-
aware for the DCSG-C, so that pixels of like color are combined.
Sampling differs from subwindowing, which picks a rectangular portion of
the image, but doesn’t change its resolution. The DCSG has one
subwindow mode, in which the center 320x240 subwindow of the imager is
chosen. Using the subwindow has the effect of zooming the image by a
factor of 2.
Figure 7-2 shows the frame size and subsampling controls on the video
capture application. With DCAM version 2.0, the sampling control has
been changed to a simple Frame Division control. For the DCSG, there are
two possible values, 1 (full image) and 1/2.
Refer to Table 4 for a complete list of allowed modes, and how the frame
size and sampling setting affect the output image. Explicit control over the
sampling mode is accomplished with the SetSample() function from the
DCAM API.
The first three lines of the table are for full-frame images. At 640x480, the
full image is sent to the host PC, and there is no binning. At 320x240, the
full image is sent to the host, where it is binned The monochrome imager
is able to perform binning on the imager, which means the bandwidth is
lower - this is the greyed line in the table.
For 1/2 frame size the DCSG transmits the center 320x240 subwindow.
7.5 Frame Rates
Frame rates from the DCSG/-C depend on the frame size. Table 4 shows
the frame rates available for each of the frame sizes. Note that a 50 Hz
option is available – see Section 3.4.
7.6 Firmware Parameters
There are several firmware parameter that affect the overall behavior of the
DCSG.
• Vertical offset of the image
• 50 Hz operation
These parameters can be changed by using the Firmware Parameter dialog,
accessible from the dcam menubar. Choosing this menu brings up the
dialog, which is shown in Figure 7-3.
The dialog lists many of the internal parameters of the device, which are
fixed in the firmware. The changeable parameters are for 50 Hz or 60 Hz
operation (Section 3.4), and for vertical offset and image inversion. The
Firmware Parameter dialog is only available after the DCSG has been
opened by pulling down the Video item of the Input chooser.
7.6.1 50 Hz Operation
To use 50 Hz operation, check the box, and then press the Save button.
This choice is downloaded and stored in the device, and will cause 50 Hz
operation every time the DCSG is accessed. To change back to 60 Hz,
uncheck the box and again save it to the device.
7.6.2 Vertical Offset and Image Inversion
The DCSG is normally supplied with the image un-inverted. For special
applications it may be useful to invert the image.
The CMOS imager has more pixels than are returned by the video stream,
and the image can be vertically offset within the frame by several lines.
Resolution Frame
(FDIV)
Bin on
imager
Bin on
PC
Frames per Second
640 x 480 Full no no 3.75, 7.5, 15, 30, 60
320 x 240 Full yes no 3.75, 7.5, 15, 30, 60
320 x 240 Full no yes 3.75, 7.5, 15, 30, 60
320 x 240 1/2 no no 3.75, 7.5, 15, 30, 60
Table 4 Subsampling modes and frame rates for the DCSG. The
greyed line is monochrome only.