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Unregistered
July 16, 2003, 15:08:08
Hi,

We use DFG/1394-1 to capture video.
The problem is the captured image quality is different with different size.

When use unproportional capture size, eg, 768*288, the image quality
is OK;

When use proportional capture size, eg, 768*576, 640*480, 320*240, the image quality is not good: when the camera is moving or there is moving object
in the image (i.e, the image is changing with time), there are a lot of small horizontal lines which blurred the object.
(We actually use the demo softerware in the CD-ROM with the device)

How can we solve this problem?

Best Regards,

James

Johannes Vogel
July 16, 2003, 17:31:49
Hello,

You see these artefacts only if you move the camera, donīt you?
This is the so called interlaced effect, caused by the fact that the odd
lines of the image are exposed 20ms (for PAL) resp. 15ms (for NTSC) earlier
than the even lines. In the "half-height" formats like 768*288, only the
odd part of the image is transferred. Therefore, no interlaced effect can be recognized.

Using a DCAM camera would solve the problem because these camera expose all lines at the same time. More information about DCAM cameras can be found on our website:

http://www.1394imaging.com/products/cameras/


Best regards
Johannes
IC Support

dzweig
July 24, 2003, 22:12:41
Hi,

We recently received a DFG/1394-1 and we are seeing the same effect.

I understand why we should see interlace artifacts at 640 x480 resoution but we are also seeing them at 320 x 240 pixels. I would expect that 240 vertical lines should all be from the same field.

Any information on this why we see this at lower resolution would be appreciated.

Best Regards,

Dave Zweig

Johannes Vogel
July 25, 2003, 08:43:46
Hello,

The format 320 x 240 is an interlaced format. The only way to get a field based image is to use a 'half-height' format like 640 x 240. These images have to be scaled in horizontal direction in order to get a correct aspect ratio.

Best regards
Johannes
IC Support