HD vs SD

[Daz]

Has anyone done a High Definition programme which has then been broadcast in Standard Definition?

Well, you would think that would be just about every HD TV programme ever made. But working on "Geldof in Africa", a 6 x 30min series for the BBC, we've just struck a rather odd scenario. Having lovingly graded the first few programmes, we struck an SD copy which, by comparison, appeared to be washed out, set up, undersaturated and colder than the HD original.

Well, naturally you would expect an SD version of the same shot to look inferior to the same shot in HD. But surely it should have the same degree of colour saturation and colour balance? We then looked at several other unrelated programmes also filmed in HD, only to see the same effect on SD. How odd. How annoying! Anyone else seen this?

daz

[Daz]

These responses from the Avid-L:

Subject: Re: HD vs SD
From: "Robert M. Malachowski, Jr."

Star Trek enterprise had the same problem when they first started airing off
the HD broadcast master. There were hundreds of complaints from the fans.
The broadcast show exhibited some of the same problem you are mentioning.
At the same time, when I did American Fighter Pilot, we delivered HD masters
to CBS who then did the downconverting themselves and everything looked fine
at SD at home. It looked far more brilliant in HD, but that only stands to
reason.

Subject: RE: HD vs SD
From: "Rupert Watson" <rupert@root6.com>
Darren,
HD and SD have different colourspaces; you need to have a chat to our
man Phil about this.

Did you do the downconvert on the Nitris?


Subject: RE: HD vs SD
From: TCurren@aol.com

I haven't had a setup problem, could be your downconvert. The chroma is
definitely nowhere near as saturated in SD.

It's depressing when you see them side by side. On the other hand, if
you don't see them side by side, you probably wouldn't notice. Same could be
said something shot on digibeta shown side by side with miniDV.

[JWRL]

Hi Daz.

A couple of years ago I worked on a short film called "The Upstairs Neighbour" which was shot on Super 16 and finished 1024:25p. It was subsequently downconverted for festival distribution onto NTSC DVD - about as radical a colorspace change as it is possible to imagine. We performed the conversion at Digital Pictures - AAV a local South Melbourne one-stop shop.

The end result using hardware downconversion to the 8 bit colorspace of the DVD was subjectively the same. There were motion artifacts due to the 25p-NTSC conversion, and there were (according to the DOP) some color "subtlety" losses.

I have seen often heated discussion about hi-def 10-bit to 8-bit conversion losses on various forums that I visit, but they all seem related to performing the conversion within the Edit application. I suspect that because there cannot be a linear mapping from 10-bit or better uncompressed colorspace to 8-bit compressed you should probably expect results to vary depending on the color content of the original material.

No real help I know, but maybe a blanket correction post conversion would solve your problem?

[Daz]

Yes, we ended up applying an overall grade to correct the problem in the SD online. Gave the director a chance to re-tweak some shots!

BTW, our workflow is:
shoot panasonic Varicam
conform Nitris
sneakernet the JBOD to another post house and grade on Finaliser
Create HDCAM graded master our of Finaliser (no captions)
Create SD Digibeta from the HDCAM
Create final SD master

We're holding the clean HDCAM masters for international sales & possible cinema distribution. Otherwise the primary delivery is to the BBC in SD. Part of the appeal was to be able to shoot slow motion in camera.

I've also spotted a weird solarising effect, particularly visible on rich skies. Looks mad when you dissolve as the "edge" of the solarisation wipes across the frame. Looks suspiciously like a 10bit 8bit problem.

[JWRL]

Yes, it almost certainly is 10bit-8bit. I've encountered this mainly on blues too, and also on flare around a saturated red light in shot which gave rise to a really bizarre shower of white dots around the lamp. Fortunately the director liked it - he thought that it was a special efect....