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Infrared video school, part 3: The channel mixer

The “channel mixer” is maybe the most important tool in the transformation of a typical infrared image/video (720nm) into a final product. Using Adobe Premiere we can swap the red and blue channels to change the brown sky for a dark blue one.

Although the following manual is pretty long, there’s actually not a lot to do, provided that white balance is set accurately before filming (link). Once you know what to do, the following steps will take you 10 minutes or even less. That’s all I spend for image improvements in post-production.

There are 3 steps. Taking the example of a typical infrared filter, the 720nm by Hoya (R72), I would like to explain these in detail now.

I pass those steps with the help of 2 editing programs: Adobe Premiere and the standard Apple iMovie software. Probably you can do this with other software as well.

Here’s what I do:

1. Optimize white balance in Premiere
2. Use the channel mixer in Premiere
3. Further optimize white balance and add some contrast in iMovie.

So let’s explore the process more closely.

After I’ve transferred my videos to my laptop (and saved them), I open Adobe Premiere and load a clip that shows grass or leaves. It looks like this:

 

 
I want to optimize white balance now, so I go to the section Effects, then Lumetri Color, then Basic Correction, choose the White Balance tool and apply it to a leaf or blade of grass in sunlight.

So white balance should be good now. Maybe write down the values in Temperature and Tint so you can just type them in when you process the next clips.

Next step is essential for most IR videos: The color channel mixer. Go to Effects, Effects, Video Effects, Color Correction, and select the Channel Mixer. The values should look like this:

 
Channel mixer

Now change them into this:

 
Channel mixer

The video now has a dark blue instead of a brown sky, and everthing looks more “natural”:

 

 
I now save/export my video. A short note on the format: I’ve found H.264 to be the best and most usable so far.

2 steps are done, now the last one:

I load iMovie and open up the exported video. So far, I’ve used this program also for cutting and assembling videos, because it’s much more beginner-friendly than Premiere (this will be a topic in future articles). But you can’t do channel mixing with it.

I now further enhance white balance and add some contrast via Color Balance and Color Correction.

That’s all. As you can see, I’m a big fan of minimal post-processing. It will save time and look authentic in the end.

Here’s the final result:

 

Infrared video school, part 2: White balance is (almost) everything

In a previous post, I showed you my gear and setup for filming in IR. This time, I’d like to tell you about the importance of white balance.

In my opinion, setting the correct white balance is really essential. Different IR/color filters block different light waves and hence shift the neutral tones considerably. You have to “balance” them.

You should set the white balance prior to filming and not in post-production. Setting it afterwards on the computer, for example in Adobe Premiere, will not give you good results and additional color corrections will be needed. These are time-consuming and result in huge file sizes. So do it before filming. Believe me.

It’s even more important in filming than in photographing because you can’t take videos in RAW format and then just do the trick easily in Photoshop. Video just doesn’t work like that.

In the case of IR or full-spectrum videography, setting the perfect white balance is a bit complicated, because there’s no “one size fits all” way.

 
white balance

 
white balance

 
Generally, there are 4 options:

1. You can use the presets in your in-camera settings like “sunny”, “cloudy” et cetera. But this will not be exact and won’t work at all with a lot of IR filters.
2. You can do it via “trial and error” method and go through the color temperatures (2500K – 10000K). But this is time-consuming.
3. You can use a picture (with the filter on the lens) of a neutral object (a concrete street and certain unpainted walls for example) or, in the case of strong IR (720nm and more), grass.
4. You can use a grey/white card.

Forget the first option for filming in IR because it’s not exact and won’t give any usable results in a lot of cases. The others do, but it depends on the filter. And it also depends on the camera model.

I can only tell you what works for me.

So here’s a short overview on the filters I commonly use with my Nikon D7100 and their corresponding “best way” to get the right white balance:

1. IR Chrome (red-colored trees): Just choose 10000 Kelvin as color temperature (link).
2. Super blue (yellowish or white trees): Use a grey card for yellowish tones and use a picture of grass for white vegetation.
3. Enhanced/Super color: Use a grey card.
4. 720nm (white trees): Use a grey card or a picture of grass.
5. Monochrome IR: Use a picture of grass.
6. Green filter (magenta-colored trees): Choose around 2560K (link).

You probably have several slots for white balance presets, so you should just capture and save them on one occasion. Get out on a sunny day with all your filters and a grey card and get them into your camera, so you won’t have to worry about them anymore.

The cotton candy IR look

So yesterday I tried out, just for fun and to maybe achieve a new IR look, some old filters which I had stowed away. I thought, perhaps one or two could be of use with my new Nikon D7100, because you can select the perfect color temperature manually on this model. And I found a surprising result: The green (X1) filter by Hoya, which I had bought for my Sigma SD14 (link), can give you cotton-candy-like magenta tones in the willows and trees and cyan-blue skies. I think it’s an awesome IR look.

So what do you have to do?

Set the white balance to around 2560 Kelvin and then go to the color matrix to select the square in the red-magenta corner. That’s about it. I additionally screwed on a Sunsoft Cokin filter which gave the image a more neutral, browish tone, but I’d say that’s mandatory. I also used a polarizer and increased the saturation and hues in the picture controls.

 
Take a look at the following video (external Flickr link):

Green (X1) filter

Infrared video school, part 1: The setup

I’ve started to dedicate myself to infrared video during the last couple of weeks. Filming is in many respects similar to photography. The rules stay the same regarding composition, lighting and the main functions of your camera.

On the other hand it’s very different. You have to focus on movement, your own movements and the movements of your objects and subjects. Not everything that looks great in a still image does in a video. It’s physically more challenging and you need a couple of gadgets and software to make it work.

But it has been rewarding so far and, most importantly, I could recreate (more or less) the look of my IR photographs.

So let’s start with this infrared video school, a series of posts dedicated to the hows and whys of infrared filming. In this first post I’d like to show you what kind of equipment I use and how I set it all up correctly.

This is my gear:

1. A camera (Nikon D7100) with a lens (my favorite, the old 28mm Nikkor)
2. A steadicam (unknown brand)
3. A microphone (Takstar)

You may ask how expensive this is. I bought the camera, which is a used model converted to full-spectrum photography, for around 800 dollars. The rest is pretty cheap: Maybe 40 dollars for the steadicam and around 20 dollars for the microphone. Both are great for beginners, but sure, you can find much better products.

 
infrared video school

 
infrared video school

 
The steadicam will help you stabilize your camera. Try following these steps when you’re installing the camera (with the mic) onto the steadicam:
1. Remove the strap (will sway and hence disturb the stabilization).
2. Also remove the lens cap.
3. The right amount of weights is important. You can test it by holding the steadicam with the camera horizontally and letting the side with the weights fall. It should go in around 2 seconds from horizontal to vertical.
4. Then move the weights and shift the bar holding the camera until everything is in balance. Consider marking the positions of the weights for each configuration (maybe you want to use different lenses).

 
infrared video school

 
You should test with the microphone. Not all models have the same buttons and options. These are my preferred settings:

 
infrared video school

Starting with a bee

Producing videos is a whole new world to me. It’s much more complex and exhausting than still photography, and IR adds another level of complexity. You need a camera, a steadicam, a microphone, you need a video production software, where you can merge, cut and brighten up your footage and where you can do the channel mixing associated with infrared imagery. In the coming weeks and months, I’ll write sporadically about my experiences and troubles with filming in IR light, about the gear I use and how I process the images.

For the time being, I’d like to show you the first decent footage. I’ve recorded it with a steadicam and did a bit of proper post-processing. It’s a bee, in 720nm infrared, recorded at Lake Uebeschi in Switzerland with a Nikon D7100 and an old 28mm Nikkor lens…