Sensor size of the HVX & Pre-filtering - what would we get w/out pre-filtering?

F

filmguy123

Veteran
OK, so I understand that the HVX prefilters in order to save space and fit into the 100mbps stream of DVCPRO-HD. But, what is the HVX gathering natively, before pre-filtering? Is it 1920x1080?

So I am wondering, if the HVX200 was upgraded (theoretically) to support AVC-Intra100, would it be capturing a full, native 1920x1080 frame live the EX1 is, since it would no longer have to prefilter?

Also, does this mean that currently, the pixels on the HVX200 are smaller than they need to be? More pixels = Smaller pixels = lower sensitivity; but if there are more pixels there than be used, does that mean the HVX is, in a sense, throwing away sensitivity (ie, could have just captured less pixels, meaning bigger pixels, meaning higher sensitivity, and same resolution, since currently it is pre-filtering anyway?)

And, if it were upgraded to support AVC-Intra100, could the HVX200, as is, produce a full-frame native 1920x1080 without "adding" more pixels, ie, with no decrease in sensitivity (since the pixels are already there, but thanks to AVC-Intra100, would no longer need to be pre-filtered?)
 
Pre-filtering is an operation of the codec, not the internal processing. Internally the HVX always operates at 1920x1080.

However, the spatial offset system combined with the pixel count of the chips means that it delivers about 1440x810 of real-world res. That was apparently decided as a great compromise considering that the recording format wouldn't support more than 1440 wide anyway. Remember, these systems are designed as a comprehensive solution, and the engineers must have felt that there wasn't much reason to go beyond 1440 resolving power since the recording codec didn't support more than 1440. So they were able to make the pixels as large as possible to take advantage of the sensitivity and contrast boost that larger pixels can give.

As for your last question, it's irrelevant -- it's like "could superman beat up mike tyson?" AVC-Intra is not an option for the HVX200 and probably never will be. By the time AVC-Intra is brought down to an HVX-priced system, it won't be the HVX200, it'll be the HVX250 or HVX300 or HVX400 or who knows what. And presumably that newer model will be designed to take full advantage of the recording codec's potential.
 
Hi,

Keep in mind that the codec is the prefilter not the camera. It doesn't matter whether the camera is the HVX200 or the HPX3000. The DVCPRO HD codec prefilters the high frequencies that would only become problematic in compression. This happens in many of the the high end codecs, including HDCAM. It is an important process, in as much without it you would get compression artifacts.

The CCD is an anaolg device. The image that comes off of the CCD is complimented by the additional information given to it by the spatial offset. that is then captured at 1080X1920. It is then processed throughout the rest of the camera chain in this fashion. Then it enters the codec world and it starts the process, of prefilter, to DCT, ..and onward to ... DVCPRO HD.

Prefiltering works to compliment the compression.

Best,

Jan
 
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