[Tig] RE: Compressed Grade Transfers

Dominic Case dominic_case
Mon Nov 5 23:46:08 GMT 2001

Rob asks:

>Are there penalties paid later in dynamic range ?

Good discussion point, Rob.

Yes, of course there are. In digital terms, if you stretch the restricted
range you are going to use over the full 256 values, you will get better
tonal detail across the scale later on, than if you pack the whole film into
256 values, then only select 200 of those values later on and pull them back
out to 256.

The problem is, knowing which part of the tonal range are you going to use.
If everyone got everything right first time, no-one ever changed their mind,
or had a difference of opinion, and could always visualise how the entire
show is going to end up in terms of every element of every shot, then we
wouldn't need any tape-to-tape correction anyway. But as soon as you change
anything in the second grading pass, you end up trying to expand one end of
the scale that you have previously crushed or even clipped. 

> It's my humble opinion that we try to mimic the dynamic range 
> of film in 
> video not by showing all the (limited) dynamic range

I think the purpose of the compressed grade is not to "mimic" the dynamic
range of film, but to "use" the dynamic range of film to best advantage.

As you will have gathered from the direction most of the replies on this
topic are coming from, the compressed grade technique seems to be widespread
in Australia - and other places. I like Mike Most's term Video Interpositive
(VIP). If you know how film duplication works, it's an excellent metaphor.
Compressed versus uncompressed is similar to transfering from interpos
versus transfering from print. Both work, but you have more room to move
with an interpos.

Dominic Case
Group Technology & Services Manager
The Atlab Group
87 Mars Road, Lane Cove 2066
ph +61(0)2 9906 0100
fax +61(0)2 9906 7048
email: cased at atlab.com.au
web: http://www.atlab.com.au

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