Auto Lut on monitoring

Forum|Forum|3 years ago
February 15, 2023
2 replies
824 views

Hi,

I met a problem with a footage in slog3/sgamut3

When I read it from the original footage in premiere (left monitor) I see the log. When I read it in the time line, I see it with a lut.

The option ''disable masterclip effect'' in the project are not choosen for this clip.

How have it without lut on the timeline?

Thanks a lot

This topic has been closed for replies.

R Neil Haugen

Legend

For that clip, it is not applying a LUT anywhere ... there are several other types of transforms, and they use an algorithm, a very complex mathematical formula, to normalize the S-log3.

If you select one or more similar clips in the project panel bin, right-click/Modify/Interpret Footage, you can set the Override-To option to a couple different S-logs. Use the correct option.

Then depending on how the Log Color Management switch is set in the Preferences/General tab, you can get two behaviors.

- Log CM on: they use their normalization algorithm to normalize the clip to the working color space.

-Log CM off: you should see a 'log' image, uncorrected, in an SDR/Rec.709 working space timeline.

Some general information that seems unknown by many, so I'll add it as it may be of use to some reading this. Log media is not designed to look "log". It's simply an encoding process to get a wider dynamic range of data recorded to the file.

The camera makers assume it will be essentially "un-logged" or normalized in the CM system during processing, returning it to a more normal actual image.

There is no perfect normalization for any log media, and never has been. Only ones that may work better for this clip than that clip, even when using manufacturer provided LUTs. As LUTs are built from test media shoots with typically perfect exposure/contrast/WB lighting. And matching perfect camera settings.

It is rare for field-produced media to match that perfect 'test' media.

And if any of those is not perfect with your field-produced clips, then the LUT may clip, crush, or just do something not great. So many colorists have several different LUTs or various other choices for normalizing each type of log encoding they work with. And select whichever works best with each clip.

And sometimes, they simply use the built-in normalizations as feeling they are "as useful as any other starting point" ... and quick to get going with.

The algorithms that the Premiere team have delivered are very solid mathematically and superior to most LUTs, as they cannot clip or crush data. Yes, they deliver a slightly different "normalized" file than you may be used to from a LUT based normalization ... but it also might be a better file data-wise.

So ... the user always has a ton of choices.

Neil

Everyone's mileage always varies ...