PCI 1411 acquisition window values setup

[ann]

Which is the relation between the acquisition window parameters left, top, width, hight of the acquisition board and the image size due to the standard video signal? Is there a way to calculate their maximum values knowing the image size (for instance 768*576 of PAL or 640*480 of NTSC)?

[Yusuf C]

Hello,

Left and top are the horizontal and vertical offsets respectively. Width and height is the same as image width and image height (same as the active sensor area). In order to properly set these values (in the case of an NTSC camera) you should start by setting the parameters as follows:
Left: 0
Top: 0
Width: 640
Height: 480
Since this won't have any offset you're likely to see black bands on top and left of the image acquired.
While doing a grab increment the Left and Top offsets until you get rid of the black regions.
Hope this helps!

Best regards,

Yusuf C.
Applications Engineering
National Instruments

[ann]

Hi thanks for your answer. I have a PAL camera therefore the image size should be 768*576 but if I set left and top at 0 I can increase width and height till 932 and 617 respectively. May you tell me why?

[BruceAmmons]

The camera usually sends extra blank lines, and the ends of each line are also blank. It is possible to capture these blank areas with the frame grabber, but it doesn't do you much good.

Typically there is a small amount of image that can be added by increasing the size by a pixel or two. However, when you do that you aren't using the standard size any more, which most people will assume you are using. If anybody else tries to make changes to the software, it could confuse them.

Bruce