Color Grading Slog Video - Without the Headache

For me, Slog profiles are both a siren and a curse.  I'm drawn to the promise of greater dynamic range and the protection from blow-outs; I'm demoralized by the difficulty of transforming Slog 2 and Slog 3 footage into vibrant, rich video.  Admittedly, I'm not the greatest of color graders; most of us aren't.  In fact, I suspect that much of the "stylized" color grading I see is simply an effort to cover up the fact they couldn't create a natural looking image.  I'm sick of green-hued images.  But I can't throw stones because I have the same difficulty-- even after 20 minutes of futzing with levels, color wheels, and contrast, I'm dissatisfied. So what the heck is wrong with Slog footage and how can I grade better and faster?

I don't have an answer to the first question.  The problem is probably me.  To give myself a break, photos are rarely as pug-ugly as Slog 3 images, and the tools in Lightroom and Photoshop are much much better.  But I have figured out a great way to quickly grade my footage to an even more satisfactory level than before. 

Personally, I think the Sony a7Sii color is a bit wonky.  Not all the time-- but sometimes there's a muted hue, and it's on full display when you color grade from Slog. So here's a technique I've discovered:

1. Before shooting your footage, take a photo of the scene.  Make sure it's properly exposed, since your camera settings for Slog may be too far to the "right," i.e. slightly blown out for still photography.
2. Now film in your Slog profile of choice.  Whenever you move to a different scene, take another photo.
3. Import both the photo and the video into your video editor; I use Sony Vegas Pro.
4. I believe all the major editors have a color-match function.  In Sony Vegas, open the Color Match FX to apply the photo color to the video. Be sure to tick the "match brightness" box.  It should look like this:

 

If you're unfamiliar with this tool, I'd suggest Google for a more complete explanation.  But quickly, the Source Image will be your photo (the color you want); I make sure the still image is on the Preview screen and then click "Preview" to capture it.  The Target is your video; I bring up the video on the monitor and hit Preview in the Target box.  The color adjusted image will appear in the Result section. 

This will get you 80% of the way there.  Typically, I use the Levels FX to bring the image into perfect exposure.  If you don't know how to use a Waveform scope, learn, because it's amazing.  And for a little extra punch I'll boost the overall saturation using the Color Corrector, and individual colors using AAV Color Lab.

Here's a before image of the footage:

It's the typical washed out footage of Slog 3.  Now here's the color matched and tweaked image:

The great thing is that this only took an extra 15 seconds during filming, and about two minutes of grading in post. After tweaking the levels and saturation, the resulting image is better than the original photo.

While I've known about the Color Match feature for a while, I only now just thought to apply it to my Slog footage utilizing a reference image.  It's really the same technique film photographers used to employ, taking a Polaroid to check exposure.