Phytec pciGrabber4x4, Руководство по оборудованию

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Programming Manual
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PHYTEC Messtechnik GmbH 2008 L-720e_0
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The value ppl and lines define how many pixels should be generated
from the incoming video picture. ppl indicates the number of pixels
per line, and lines determines how many lines (pixels in y-direction)
are produced. Both values indicate the resolution of the image.
A whole frame in PAL format has 720 pixel x 576 lines. In order to
digitize the image with the highest resolution,
ppl will be 720 and
lines = 576. The smallest resolution for PAL is 50 x 40 pixels per
frame.
If fields are used, the maximum resolution is 720 x 288 lines.
Since the definition of
ppl and lines always refers to fields, the actual
number of lines of the TV-picture to be digitized is twice as high. The
width/height ratio for the digitized field (maximum 720 x 288 pixels)
gives a distortion of two in y-direction. In order to avoid this effect
digitization is done in interlaced mode (if the high resolution is
required) or you can reduce the resolution to
ppl =360, lines =288 and
the resolution will be proportional with 360 x 288 pixels.
Note:
For stereometric work or automatization applications, a correct
proportional resolution is not always required, as long as the distortion
is taken into consideration in the algorithm. So the complete field
resolution of 720 x 288 can be used for stereometric work, which is
more accurate in x-direction than in Y-direction. It is also possible to
adjust the axis of the camera in the direction the measurement has to
be taken.
The window with the proportions hsize x vsize is a section of the
digitized image, which has the size ppl x lines. If hsize = ppl and vsize
= lines the whole digitized image is displayed. If this parameters are
smaller, only a section of the image is displayed. The ratio of hsize to
vsize does not alter the proportions of the image, since no scaling
occurred and only a certain section of the image is taken.
Figure 47
and Figure 48 demonstrate the significance of the
parameter.