Need to soften your footage or add a dramatic glow? Follow these quick tips to add diffusion to your project.
Top Image via Paramount Pictures — Morocco.
I’ve always been a huge fan of the diffused film glow in many films from Hollywood’s Golden Age. Filmmakers would create this haze by placing silks and nets behind the lens. The primary reason for this was to soften the skin of the Hollywood starlets. Fast-forward seventy years, and you can find a whole array of different diffusion filters that can make your images glow. You can find my write-up about the world of diffusion filters here.
Image from Rebecca.
While there are third-party plug-ins to add a digital glow to your footage, I have found that many tend to add an incandescent blur to the entire image, which doesn’t look the same as placing netting behind the lens.
To digitally reproduce an organic-looking haze, you want to aim for a gauze effect that softly applies the glow to lower the overall contrast and create a dream-like or romantic look. Like everything in filmmaking, there are several ways to achieve this effect, but we will look at two in particular — first in DaVinci Resolve, then in After Effects.
Adding Diffusion in DaVinci Resolve
One way to create a controlled, subtle glow is to manipulate the settings of the HSL qualifier controls. In our case, the blur. Note that this effect raises the highlights and part of the midtone region, which is something to consider when you’re initially grading your image.
You should only create this diffusion for a fully graded image, so make sure it’s the last thing you do.
Let’s get to work.
Set your selector to the HSL, and use the luma qualifier to isolate the highlights of your image. Adjust the softness levels to extend the highlights just into the midtones.
Increase the Blur
A lot. I find that somewhere between 150 to 200 creates a good effect.
Create the Organic Glow
We’re just going to raise the midtones and increase the highlights. The larger the blur area and the more extreme the effect is, the more the glow will bleed out of the highlights and into the midtones. Be careful with this since you could just end up applying a glow to the entire image.
If necessary, you can also add some color to the highlights to blend the glow. This is also a handy method to hide overblown highlights, a tip I covered here.
Adding Diffusion in After Effects
If you don’t work with Resolve, we can create the same result in After Effects. You can easily create an organic-looking gauze effect by blending two layers together.
After grading the clip, create two copies in your timeline.
Add a Gaussian Blur
A blurriness setting from 5-10 works well. The setting will depend on your shot type.
Change the Blend Mode
Of course, this doesn’t look that great. Our entire image seems a little out of focus. You just need to simply change the blend mode of the top layer to lighten.
Now our image has a beautiful, soft haze. If the initial effect is too strong, you can either adjust the amount of blur on the effects layer, or you can change its opacity. When employed in real-time, these techniques can take just a few minutes, they don’t require a third-party plug-in, and the diffused glow looks similar to the haze found in films from the 1940s.
This technique isn’t for every shot. It’s a digital tool that has a use just like every other effect you may know. However, great uses of this technique include creating a dreamlike image, a romantic scene, or a scene set in the early 20th century.
Have you had success adding diffusion? Let us know in the comments.