Re: [Openexr-devel] Re: [Openexr] KeyKode offsets

[Daniel Fort]

Hi Thomas,

Your explanation makes it clear  why perf offset is significant on film 
cut lists even on standard 35mm 4-perf.

In this day of digital intermediates it isn't really necessary to cut 
the negative before scanning. But when working with uncut negative, how 
does the equipment know where the frame lines up? It is standard 
practice to unthread the film between camera setups when "checking the 
gate." One of the jobs of the assistant editor is to cut the workprint 
before screening dailies to make sure it is all "in frame" for the 
screening. A film scanner cannot make these judgments and needs to be 
told where to frame up. The problem gets even more involved when 
dealing with lab rolls made up of spliced together camera rolls and the 
second perforation offset value you mentioned comes into play.

This is all good information to help understand why perf offset is so 
important to scanned images. I think the developers are on the right 
track for including it in the key code field for OpenEXR.

--Dan

On Sep 29, 2004, at 4:13 AM, Thomas Kumlehn wrote:

> Dear Ken,
> dear Dan,
>
> in fact handling film footnumbers digitally often needs two perforation
> offset values:
> ...