FX1: High-def..... FX1's color: Low-def?

Ryan_W

Ryan_W

Active member
I'm thinking about a very small project right now with some very specific and unusual needs. I'm simply looking to extract the best chroma keys I can, and the rest of the information, such as latitude, sharpness, framerate, etc are all secondary. I don't need it to look like film, in fact I don't need it to look very good at all... All I'm interested in is getting the cleanest keys I can, so I can use those mattes for motion graphics needs.

Now, I know the FX1 is HDV and sports a few more pixels than something like the DVX, and I also know that it does this with a lessened colorspace and MPEG2 compression. And so the actual useable color information may not be quite so 'high-def'. The end result will be broadcast resolution, however. My hope was that once the HD-res key is shrunken down to TV-size it would look better than a TV-res key. But this may not be so, if the color info is overly strained in the HDV format.

So what I'm wondering is..... am I better off going with lower-compressed lower resolution, or higher-compressed higher resolution?
 
Hi Ryan,

if you can and you need the material only for keying: Don't use the FX1. It has a magnificent picture and in spite of all the bad buzz done here it is a great camera. But as you mentioned it uses MPEG compression for an anamorphic picture.

The chip itself has (as far as I know) 980 active pixels. They are exposed through an anamorphic lens and the result is being sampled to 1440 per 1080 pixels. So there already you have a lot auf artifacts talking about long lines in every field where there is movement of one solid colour against the other. It will be put anamorphic again in you NLE to get the 1980 pixels width of 16:9 1080i. So the artifacts get even longer. As we know HDV compresses colour in a 4:2:0 subsampling. (i.e. 22:11:11 in HD) so after all I am not sure, but keying with this seems a bit hard for me (having done it several times now using my Z1's footage.)

Still: If it's SD only: Deinterlace the HDV, loose half the resolution which is no loss in SD and do teh keying. Could work fine.
 
The new Mary Poppins DVD uses new chroma key'd video from Digital Betacam. Why?
Digi-Beta is a 10Bit 4:2:2 format, with a 2:1 compression v. HD options, it uses less compression.

So--I think that's a good example to say that lower compression is better than higher resolution,
at least for the purposes of Chroma Key.
 
Ah. I suspected as much. My friend has a euro XL-1, which is 4:2:0, if I recall correctly. That would be better than 4:1:1 for color, wouldn't it?
 
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