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Old July 24th, 2004, 05:17 PM   #1
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Uprezzed?

What does it mean when footage is uprezzed?
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Old July 24th, 2004, 06:23 PM   #2
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DV is 720x480 (US) or 576 (europe) pixel.
This is good but for video on small screen.
If your target is big screen and/or conversion to film, there are chance you want a better picture.
Another situation would be the FX section who need hires picture to apply effects.
you can easily do this by saving your video in a serie of pictures (preferrably uncompressed tiff or bmp , no jpeg please) and increasing the size of each picture with special software (like photozoom, former S-Spline).
You can then reconvert to video.
Even when reconverting back to original size you can get improvement.
with DV, uprez is limited in a way that chrominance is half resolution of luminance, so uprez is less efficient.
additionaly you should make sure your video is progressive or deinterlaced, because scaling interlaced frame usually give unworkable results.
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Old July 24th, 2004, 06:30 PM   #3
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The chroma on many digital video sources is at a lower resolution than the luma, and DV is particularly bad in this regard. But if you reconstruct the chroma beforehand, then things can work very well.

Most video software will uprez video taking into account the field based nature of video making de-interlacing unnecessary. If you go down the photoshop route, however, it doesn't understand interlacing so you'd need to de-interlace first.

Graeme
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Old July 24th, 2004, 06:44 PM   #4
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if you got name of softwares that uprez directly to video, i would be happy to know.
Thanks
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Old July 24th, 2004, 06:56 PM   #5
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After Effects, Shake, pretty much any compositing package will do it. I have a chroma reconstruction tool for FCP that you could use before-hand, but if you don't have that, use a DV codec that interpolates the chroma - I think the Avid one does that, or just do a 4 pixel horizontal blur on the chroma channels.

Graeme
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Old July 25th, 2004, 02:04 AM   #6
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Graeme, can you give detailed steps for the process. I have Shake 3 & AE 5.5. Do I use the chroma node in Shake? If so, what are the settings?
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Old July 25th, 2004, 09:30 AM   #7
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On Highend 2d there are a number of chroma-reconstruction filters. The upsacling in Shake is pretty good without 3rd party software. I wrote a much more complex and higher quality algorithm for FCP that I hope to port to shake once I've learned the SDK: http://www.nattress.com/filmEffectsGNicerTests.htm

Graeme
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Old July 25th, 2004, 01:34 PM   #8
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This there a demo version of the filter available? I'd like to see it in action.
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Old July 25th, 2004, 03:24 PM   #9
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If you're running FCP, you can get it in the demo of Film Effects. I'm hopefully going to code a better version for Shake as soon as I can get my head around the shake SDK....

Graeme
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Old July 27th, 2004, 10:03 AM   #10
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when you talk about uprez is this only done when tranfering dv to film or other large screen format only? or do you do it to improve the picture and then resize to its original size? will it aid my picture if its final output will be beta sp and dvd for TV broadcast? thanks
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Old July 27th, 2004, 10:10 AM   #11
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Uprezzing will not help for Broadcast or a BetaSP dump. BetaSP is lower resolution than DV anyway, and a digital broadcast is the same pixel dimensions as DV.

If you want to improve the quality of DV, then you can upsample or reconstruct the chroma, but that's only of use if you're going to a verifyably higher format such as DigiBeta or HD. Using a simple linear chroma upsample will help for going to DVD though, as it has a higher chorma resolution in the horizontal direction.

Graeme
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Old July 27th, 2004, 02:00 PM   #12
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I read uprezzing and going back to 720x480 in After Effects can be done. Is this done by using a filter/effect or because of the codec being used?
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Old July 27th, 2004, 02:13 PM   #13
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Uprezzing can be done in practically any software, AE included. AE's actually pretty good at it, as long as you turn on high quality for that layer. I don't see any advantage in uprezzing, just to return to the footage's native rez though.

Uprezzing, algorithm wise, is usually a trade off between sharpness / blurryness and edge ringing caused by the interpolation filters. I have a long term R&D project to uprez in an entirely new way, and it's working well, but I need to spend a lot more time coding it before I have something that's usable, never mind commercial!

Graeme
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Old July 27th, 2004, 02:21 PM   #14
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The guys who made www.marlathemovie.com say they used uprezzing and downrezzing in their process to smoothen out details, perhaps almost like bluring layers?

Would there not be some benefit increasing the resolution of the chroma channel before burning to DVD?

Giroud Francois's earlier post said you could get some improvement even if going back to the native resolution - I guess I'm just trying to see if I can do my own experiment but I don't know that After Effects will enchance the chroma channel on its own without applying a subtle pixel blur on it.

Any feedback would be highly appreciated. Thanks.
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Old July 27th, 2004, 02:36 PM   #15
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I don't see any difference between normal noise removal processes and an upscale/downscale.

Uprezzing the chroma for DVD transfer is a different issue - I have a special plugin for that, but it's really for going to DigiBeta or HD, although it works very well for DVD I find it a touch overkill.

Graeme
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