Guest post by Justin Nederkoorn,
travel photographer and videographer

Capturing the mesmerizing beauty of aurora borealis on camera is an incredible experience. The vibrant colors, dancing lights, and ethereal atmosphere create a captivating sight. But the journey doesn't end with filming the phenomenon; it continues during the editing process, where we enhance the visual impact of the footage. In this article, we will explore the art of editing aurora borealis footage, guiding you through the process step by step.

Chapter 1: Working with DaVinci Resolve

When it comes to editing software, DaVinci Resolve stands out as my preferred tool. Although the techniques discussed here apply to any editing software, I highly recommend using DaVinci Resolve to follow along.

Chapter 2: Creating Our Node Tree

To achieve the desired visual impact, we will construct a node tree in DaVinci Resolve. This node tree allows us to make adjustments and apply effects to our footage. For my own personal editing workflow, I rely on the same carefully constructed node tree that ensures comprehensive and effective grading. By adopting this node tree layout, you can follow the editing process and achieve great results in your own projects. Let's explore the structure of our node tree:

1. ACES IN: This serial node converts our footage to the ACES color space.
2. DENOISE: Using Neat Video's advanced denoising capabilities, this compound node reduces unwanted noise for a clean result.
3. LGG: This serial node makes basic adjustments to tonal contrast and ensures a cohesive result.
4. GRADE: This is where the magic happens. It’s the node where we enhance the overall aesthetics of the footage.
5. ACES OUT: After grading, this serial node converts the footage back to its original LOG color space.
6. LUT: This node applies a Look-Up Table to seamlessly convert the footage to the Rec.709 color space for compatibility.
7. VIGNETTE: This parallel node adds a subtle vignette effect, directing focus towards the aurora borealis display.
8. OUTSIDE: Aligned with the vignette serial node, this outside node further enhances the vignette effect.
9. ADJ: Within this parallel node, we make localized adjustments to enhance specific areas of the footage.
10. FINETUNE: In this serial node, meticulous fine-tuning is applied to perfect the footage.
11. GLOW: This parallel node creates a delicate glow effect, adding depth to the footage.
12. HALATION: This parallel node introduces a halation effect, enhancing the dreamlike quality of the footage.
13. FINAL: This serial node allows for any final adjustments to perfect the overall grade.
14. GRAIN: This parallel node applies a subtle grain effect, adding texture and a cinematic touch to the footage. Note: In the case of aurora footage, this step is placed after the denoising node.

By adhering to this node tree layout, we cover all essential aspects required for a comprehensive grade on our footage. The arrangement of nodes ensures precise control over color, contrast, vignettes, localized adjustments, and atmospheric effects, resulting in a final product that truly does justice to your captured footage.

In the following chapters, we will dive into each node, explaining its purpose and how we utilize it to achieve our desired results.

Chapter 3: RAW Conversion

Before editing our ProRes RAW footage, we decode it in DaVinci Resolve by selecting the "Decode Using: Clip" option. This enables individual changes to each clip. We convert the color space and gamma to Blackmagic Design to preserve dynamic range and lay the foundation for color grading in ACES.

Next, we make initial adjustments to optimize the footage. We fine-tune the color temperature and tint, typically using 4000K for aurora borealis footage and adjusting the tint to reduce saturated green tones. Increasing the exposure by one stop brings out highlight details. We also adjust highlights, gain, and contrast to enhance color contrast. Lowering shadows slightly helps manage noise in shadow areas. These adjustments set the stage for subsequent grading and enhancement.

Chapter 4: Working on Our Nodes

In this chapter, we'll explore the essential steps for grading aurora borealis footage by addressing our nodes one by one. As you’ll see in this chapter, we address the nodes in a different order than the order in our node tree. The reason for this is that there is a specific order of nodes in which the image is processed to make sure the best dynamic range is preserved. However, tackling them in a different order and doing color space transformations and LUTs early on will help us get a better picture of the delivered image. Then we can work on correcting our image (LGG) and our color grade.

Setting Up Your Scopes

Before we delve into grading, it's crucial to set up our scopes for accurate color analysis and adjustment. By using the right scopes, we can gain insights into our image's color distribution, luminance levels, and color balance. I prefer to have four essential scopes readily available: Parade, Vectorscope, Luma Waveform, and RGB Waveform. Each scope provides unique information that helps us make informed grading decisions and maintain consistency across our footage.

Parade: The Parade scope displays color distribution along red, green, and blue channels, visualizing tonal values and color balance. Observing waveform patterns helps identify channel imbalances for precise adjustments and a visually appealing image.

Vectorscope: This powerful tool analyzes color and chrominance information. It presents color vectors in a circular diagram, with the center representing neutral colors and the outer edges representing saturated colors. By observing color distribution, accurate and consistent hues can be achieved for a harmonious color palette and vibrant aurora borealis footage.

Luma Waveform: Provides a detailed view of luminance values, helping identify overexposure or underexposure areas and predominant colors in tonal ranges (shadows, midtones, highlights).

RGB Waveform: Similar to the Parade, the RGB Waveform visually represents color and luminance values. It displays red, green, and blue channels layered, allowing assessment of color balance.

ACES IN

Our edit begins with the ACES IN node. We use it to convert the footage from the Blackmagic Design Film Gamma into the ACEScct color space. ACES (Academy Color Encoding System) provides a standardized color management system that offers numerous advantages, such as wider color gamut and improved color accuracy. By utilizing the ACEScct color space, we can maximize the dynamic range of our footage and ensure a solid foundation for subsequent color grading.

To set up the ACES IN node in DaVinci Resolve:

1. Find "ACES Transform" in the Effects panel.
2. Drag and drop the ACES Transform effect onto the new serial node.
3. Select the latest version of ACES, choose the appropriate Input Transform, and set the Output Transform to ACEScct.

ACES OUT

When delivering the footage to SDR screens, we need to transform the ACES color space back to Rec.709. To accomplish this, we use another ACES Transform node. Set ACEScct as the Input Transform, and then select the corresponding Output Transform based on your camera. In my case, since I shot on the A7SIII, I chose the Sony SLog3 SGamut3Cine. Converting my footage back to the SLog3 color and gamut space allows me to use my LUT designed for the SLog3 workspace.

Alternatively, you can also convert back directly to rec.709 or rec.2020 if you're delivering HDR content.

If you wish to apply a specific LUT in your library, convert the footage to the color space required by the LUT.

DENOISE

Before we start working on denoising our footage, let me explain briefly why the denoise node is in this particular position, and why it’s a compound node.

Neat Video works best on rec.709 footage, so we convert our LOG footage from ACES to linear gamma using a color space transform. Then we apply the denoise node, which we'll discuss further. After denoising, we convert back to ACES with another color space transform. While this all sounds very technical, we have a great article that explains this further.

Learn more at /blog/post/nv-rs1.

Now, let's focus on creating a noise profile. Select an area with uniformity across Y, Cr, and Cb channels. Larger areas yield better results. Neat Video offers guidance on the uniformity and noise intensity estimates.

Build the initial noise profile by selecting "Build Profile." Fine-tune noise level using Profile Check mode. We then use the Profile Check and Tuning options to fine-tune the noise level. Start by selecting "Begin" to observe the effect. Use the Y, Cr, and Cb channels to assess the impact while adjusting the noise level slider. Find the balance where most noise disappears without sacrificing detail.

In the Adjust and Preview section, you have an option to tweak the filter settings to achieve the best result. Use a radius of 3 to 5 for the temporal filter. I chose 5 for maximum noise reduction (however, that not always necessary). Increase Jitter of Details to about 80%, but beware of losing fine detail, especially in stars.

If you have any some remaining noise, you can eliminate it with the spatial filter. Adjust the luminance channel in the Y Enhanced view. Be cautious to avoid a blotchy appearance. Set chrominance channels (Cr and Cb) to 95% to remove color noise while preserving details.

Fine-tune noise reduction with the noise level. I’ve set it to 40%. Enable artifact removals: keep dots at 5% to preserve stars and increase lines to 70% for artifact removal.

Once denoised, apply the effect to your clip.

Pro tip: Create a shared node of the denoise profile for multiple shots at the same ISO. Right-click the node, save as a shared node, and apply it without individual profiles.

Unless you have powerful hardware, disable the node temporarily to reduce system stress. You can comfortably color grade other clips, knowing the denoise profile will handle introduced noise. Enable the node before exporting your project.

Applying a LUT

To have a better understanding of the overall look and feel of our footage, I recommend applying a Look-Up Table (LUT) early in the grading process. A LUT allows us to preview the footage with a specific color transformation, giving us a quick glimpse of the final result. To apply a LUT, locate the corresponding LUT node in DaVinci Resolve and drag it onto your LUT node.

LGG

Moving on to the LGG node, we have the opportunity to make basic adjustments to the tonal contrast of our footage. LGG refers to the Lift, Gamma, and Gain wheels, which allow us to control the shadows, midtones, and highlights respectively. To increase the contrast and make the aurora stand out even more, I recommend dropping the Lift slightly while increasing the Gain. This adjustment helps push noise into the blacks and draws more attention to the aurora.

I also use my shadows and midtones to insert some blues into these tonal regions so that we have a starting image that feels closer to what I saw in real life.

GRADE

Now we need to address the specific challenges posed by the presence of purples in the shadows due to our RAW white balance adjustments, and the need for color contrast to make the aurora stand out.

I suggest adding some cyan and greens into the Lift (shadows) to counter any purples we added into the shadows.

For the gamma, I push it slightly towards blue to create better color contrast between the green aurora and the blue sky. This adjustment ensures that the skies don't appear overly green and allows the aurora to fade into a cyan color, creating depth in the sky.

As for the gain, I recommend pushing it slightly towards cyan to help the highlights transition from green to cyan and finally to blue. By using cyan, we also enhance the green tones in the highlights.

In the curves channel, I further work with contrast by applying an S-curve. This adjustment allows me to push the shadows, creating more contrast while also getting rid of noise in the shadows. Increasing contrast also means we’re extracting more color from the image.

VIGNETTE

While filming at night, a vignette is not always necessary since we already have ample shadows to work with, and our eyes are naturally drawn to the light part—the aurora. However, it's beneficial to include this node in our node tree for flexibility. For illustration purposes, I’ll apply the vignette anyway.

To apply a vignette, navigate to the Window workspace (located next to the Qualifier) and select the circle window. Position the window accordingly and use a large feather radius to achieve a realistic result. Then, move to the curves window, place a point in the middle of the curves, and slightly drag it down to attain the desired vignette effect.

OUTSIDE

To further enhance the vignette, we can utilize the outside node to affect the opposite area. This means the outside node will impact everything that the vignette node doesn't affect. Typically, I use this node to draw more attention to the subject. In the curves window, I do the exact opposite by placing a point in the middle and slightly dragging it up. This adjustment helps to create a balanced and visually appealing composition.

ADJ

Selective adjustments play a vital role in enhancing specific areas of our footage. The most important selective adjustment to work with is, of course, the aurora itself.

By utilizing the Qualifier window and the Hue and Luminance channels, we can create a mask to isolate the aurora. Take some time to fine-tune the selection using the highlight tool in your window, which allows you to visualize the precise areas you're selecting. Once the aurora selection is complete, we can proceed to the Primary Color Wheels to make adjustments.

To intensify the aurora, increase the lift, gamma, and gain values. This will enhance its overall brightness and impact. Additionally, in the curves, select the Sat Vs Sat curve to increase saturation in the unsaturated parts, ensuring the aurora appears vibrant and vivid. The DaVinci Resolve Sat Vs Sat curve is a powerful tool that allows you to control the saturation based on the existing saturation levels within the image, but be careful to use it judiciously, as it can easily be overdone. We want to ensure we strike the right balance and maintain a natural and cohesive look.

FINETUNE

The Finetune node is left open for now since we don't need to make any final adjustments at this stage. However, it provides an opportunity to work with various tools such as the Color Warper. Utilize this node to precisely match colors between clips, adjust color hue and saturation, or make any other necessary refinements. It allows for fine, individual adjustments to achieve the desired consistency. Be mindful to always keep a close eye on your vectorscope to understand how you’re manipulating colors.

GLOW

One of my favorite techniques involves applying a glow effect to the shadows. By lowering the shine threshold and changing the composite type to "Softlight," we can create a subtle yet impactful glow. Adjust the shine threshold, spread, gain, and opacity settings to achieve the desired result. I usually lower the spread, gain, and opacity to opt for a really subtle effect since this can easily be overdone.

I also recommend using the Luminance channel in the Qualifier panel to apply the glow only to the shadow parts of the image, keeping the highlights unaffected.

This technique effectively increases contrast and color saturation, contributing to the perceived depth and overall visual appeal of the shot.

HALATION

Halation is an effect I commonly use. It helps to remove the digital appearance and provide a more traditional film camera aesthetic. However, this is not an effect you want to apply for your aurora footage since it can introduce unwanted artifacts, make the aurora bloom unnaturally, and interfere with the noise in your footage.

FINAL

In the last node, we put the finishing touches on our image.

To ensure clean blacks and whites, we can use the Lum Vs Sat curve to decrease saturation in the black and white points. Additionally, the Sat Vs Sat curve allows us to decrease saturation in the most saturated parts of the image, resulting in a more subtle and natural appearance, while slightly boosting saturation in the desaturated parts. As we've worked extensively with tonal contrast and introduced saturation, this step helps counterbalance any unnatural saturation and brings the image closer to what we witnessed in real life.

GRAIN

Now, you might wonder why we would introduce grain again after denoising the footage. The reason is simple. Shooting at high ISOs often results in some level of noise, and completely eliminating it can lead to an overly clean and synthetic appearance. By reintroducing a subtle amount of fine grain using the DaVinci Grain effect, we have full control over the noise's characteristics. This step ensures a more convincing and visually appealing result that feels more authentic. I suggest you play around with the settings to get a result you’re pleased with, but I’ve also included my grain settings for reference.

Chapter 5: Final words

In conclusion, grading and enhancing aurora Borealis footage requires careful attention to detail and an artistic approach. By following the steps outlined in this article, you can bring out the beauty and captivating qualities of the aurora in your footage. Remember to experiment, fine-tune your settings, and trust your creative instincts to achieve the desired outcome. Stay tuned for our upcoming article, where we'll delve into capturing stunning photos of the aurora Borealis. We'll share expert tips and techniques to help you capture the beauty of this natural phenomenon through the lens of your camera. Get ready to embark on an exciting journey into the world of aurora photography.