Why Log? Part 4

In the past few posts I have covered raw vs. log, why shoot log, and how log works. As an editor, I need to bring this discussion back into post: How to deal with log in the edit.

First, you need to determine if log was used. A quick glance at the footage may give you some hints. Log footage usually looks washed out with reduced saturation. But since it might be possible that this may be the finished look the production team wanted, it’s dangerous to make assumptions. It’s better to get a “real answer” concerning whether log was used.

It may be an easy task. There might be log notes or maybe the director of photography, assistant camera or digital image technician will communicate directly with you regarding how footage was captured.

If none of that happens, perhaps they shot a chart that gives you some idea of how the scene was captured and what “normal” should look like. Or, depending on the camera used, you may be able to look at the metadata to determine the shooting method.

You’ll also need to figure out which log was used. Each camera manufacturer has their own custom log setup to more closely match what their image sensor is seeing. Back when you were getting the “real answer” on log, you also need to ask “which log?” For example, a Sony camera might have been set for S-log2 or S-log3.

Lastly, you need to use what you know to transform the image into the final output. If you’re doing the final finish, this probably involves applying a Look Up Table (LUT) to convert the log footage back to an image that looks more realistic and from there do your color grading to get to the final look.

A LUT gets you back to that point more easily than trying to adjust various color correction controls to attempt to invert the math I mentioned in the last post. While you can probably get there, why not just use the LUT the camera manufacturer created?

Note: It’s also possible that they used a specific profile in-camera during shooting in order to achieve a certain look. In that case, hopefully they’ll supply you with a specific LUT that both reverses the log mathematics and simultaneously applies a “look” to the footage.

The key point is not to grab just any LUT that is labeled “log” and apply it. You need to know which one to use.

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