HD1/10 and IRE values

[Ken Hodson]

Hi there David. I remember a while ago there was a AspectHD update that had an ability to capture above 100IRE levels enabling more dynamic range through post/capture (do I remember this right?). I have forgotten how this was enabled or made available. I tried searching, but couldn't quite find you info on this. Can you please explain what this update of AspectHD provides, and how one goes about untillizing this feature.
It records at on level but captures higher?

[David Newman]

This applies not just for the old JVC camera, but all HDV and P2 cameras. In computer graphics RGB 100IRE applied to an R,G,B or 255,255,255 which happens to map to Luma value in YUV of 235. All the cameras store the image in YUV, and they use luma values above 235, which are clipped of when using RGB filters in most NLEs. In Aspect HD we fix this clipping issue by using YUV wherever possible and we use video system RGB for RGB filters (which preserve the luma headroom.) This option is within the Playback Settings Window, and it is on by default.

This the probably the most underated, or at least misunderstood advantage Aspect HD has. It makes you video look better without having to understand why.

[Ken Hodson]

So it automatically gives me access to these higher values as long as I am in PPro? Does it work the same with ProspectHD?
As well what do I have to be aware of when moving into AE for post work? Nothing if I stay in the same codec?

[David Newman]

Prospect HD offer this for AE and Premiere. AE work is a little different between AHD and PHD, as only Prospect HD has an AE importer that allows you to use "vsRGB."

[Ken Hodson]

Could you take a moment to explain this "vsRGB." What is it and how does it work? Most importantly, what is it doing that AspectHD does not? Or more directly, how would I avoid pitfalls from ApectHD and ProspectHD in these regards?
PS- thanks for the time.

[David Newman]

vsRGB = video system RGB -- it has black level of 16 and a white level 235 to allow for the full dynamic range of YUV to be presented in RGB. Not really sure about the rest of your question about pitfalls. If you turn vsRGB off you will be operating as you would in normal Premiere, blessfully unaware of the extended dynamic range that that you may never see. So no real pitfalls as is all handled "under-the-hood", we dynamically switch modes as need, so you don't really need to worry about it.

[Ken Hodson]

No, by pitfalls I ment going to another application (eg. AE with plug-ins) in an advanced workflow, where obviously I would like to maintain the benefits of this extended or proper luma values. As well, I would like to understand the differences between Apect and Prospect in these regards.
Sorry I wasn't clearer.

[David Newman]

Prospect HD has vsRGB support for After Effects and Aspect HD doesn't, and of course Prospect has 10-bit etc. vsRGB is not a new concept, advanced filters in AE will support it directly, like Color Finesse support secondary correction on vsRGB levels, but non-CC tools support vsRGB as if it where cgRGB (i.e. doesn't matter -- a blur is still a blur.) All that matters is the compositor need to know what his black and white levels are for a particular project.

[Ken Hodson]

Thanks for taking the time to explain it David.
One follow up question. To enable vsRGB in AE when using AspectHD avi's, one would need to export to an uncompressed codec first? Then importing that file into AE maintaining vsRGB values?
In short how would one CC in Colour Finesse keeping the full luma values of their AspectHD footage?

[David Newman]

There are so many little features we put in over time, I keep forgetting them.

Download : http://www.cineform.com/downloads/As...terControl.zip

This download is a registry switch that turns on (or off) the AE importer for Aspect HD (just like in Prospect HD -- although PHD gives 10-bit.) Now you can control the RGB color space. With the importer active, select a CFHD clip in the porject window and press Cntrl+F (Interpret Footage), then click "More Options" for this control (see attached image.)

Pretty easy.