Correcting Dutch Tilt In HD Footage

[Jeremy Drake]

I'm currently editing somebody else's horrible footage.

 

Some of which is tilted slightly and I'm correcting by rotating and scaling.

 

My question is how far can I take this before its completely noticeable?

 

I'm not sure if 'dutch tilt' is the correct term because it wasn't done intentionally.

[Kirsty Stark]

I've been told never more than 10%, but I'm sure in many cases you can get away with a lot more... it really depends on what format it's going to be shown in, and (sadly), who is going to be watching. I always find it amusing that some "non-film" people often don't notice any difference in quality even when you point it out to them.

[Matt Read]

It depends on what resolution the footage was shot on and what resolution it will be watched on. To figure it out, divide the resolution of the raw footage by the resolution of the format you will be finishing to.

 

For example, if the raw footage is HD 1080p/i and you are finishing to SD DVD (480 lines of resolution) then you can scale the image 2.25 times or 225% without having a noticeable difference. HD 720p/i to SD DVD would be 1.5 times or 150%.

[Guest tylerhawes]

Subjectively, when I'm working with 1080p on the big screen, most Directors / DPs are loathe to go past 10-15% zoom with their footage unless absolutely necessary. After that they hit the "whoah" point because they're upset by the quality they are seeing.

 

If you absolutely must go further, it's worth considering specialized VFX tools that can make zooms look a little better, only with incredibly long render times.

[Saul Rodgar]

It also depends what format you are shooting and finishing on.

 

If your negative is 1.66:1 and you are scanning to HD which is 1.78:1 then you may have some more leeway and you may not even need to zoom in much at all if the tilt is a few degrees only. That happened to me once.

 

If you are originating on 4 perf 35mm (1.33:1) and finishing to 1.85:1, you MAY or may not have a lot more spare room to correct the image (due to lateral edge clearance) without too much zooming, also depending on the tilt of the offending tilt.

 

Native SD video formats will be less forgiving than HD obviously.

Edited May 17, 2008 by Saul Rodgar

[David Auner aac]

My question is how far can I take this before its completely noticeable?

 

I'm not sure if 'dutch tilt' is the correct term because it wasn't done intentionally.

 

It also depends on the software you use. Scaling and rotating et al don't look really good when done in editing programs such as Avid's Xpress. Much better to do it in AfterEffects or Combustion. You could also try a combination of Gaussian Blur and resharpening by UnsharpMask, something I have done for still stuff with some success. Never tried it on video though.

 

Cheers, Dave