Phytec eGrabber-4plus, Руководство по оборудованию

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Driver Software
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PHYTEC Meßtechnik GmbH 2004 L-608e_4
175
With the call Set_Channel(1,1) channel 1 is selected for the
Grabber
#1. Digitization will take place for this channel. The
following delay is used to synchronize the Grabber to the signal of the
camera.
The next function is quite complicated: With the routine
Set_Image(1,...) the parameter of the image for the Grabber #1 are
set. We want to digitize only one even field. Therefore the parameters
for the odd field are not required and are set to zero (zero means, that
the values in the video processor are not changed). It is important to
set the pointer of the odd memory region to NULL, which is an
indication to the Grabber, that no odd image has to be produced.
For the parameters of the even image, first the position of the section
of the image is defined. The coordinates of the left upper corner
are (1.1), so that the section will be found also in the upper left corner
of the TV-picture. (Caution: (0.0) will leave the values unchanged,
which were set before.) As demanded in the problem, we now define
the number of pixels required for the resulting image of 256 x 256.
The field delivered from the source will be digitized with the complete
size of the format with the ratio 4:3. Therefore the size of the image
will be set to 344 x 258. A maximum of 360 x 288 would be possible,
but 344 x 258 is more suitable because the whole height of the image
will be visible in the section. Since the width of the image is different
in the right region 88 pixels will be invisible.
With
RGB24
the color format for the even image is defined. Per pixel,
three Byte are created, one for each red-, green- and blue value
(see also the instruction Set_Image() and Figure 48).
As pointer to the image memory region
pEWert
will be provided,
which will point to the beginning of the defined array.
For the determination of the video processor setting by the driver, the
applied video system must be known. For our example we assume a
PAL-camera as image source, and therefore
PAL_BDGHI
is set.