Join Chris Meyer for an in-depth discussion in this video Bilateral Blur, part of After Effects: Insight into Effects.
Bilateral Blur was introduced in After Effects CS4. It's an intelligent blur in that it keeps the luminance information and therefore sharpens the image, but blurs the color information and you can set a threshold for how much information is retained. It's a little non-intuitive to use. The default settings are little bit strange. So let's spend a minute, explore it, so that you can better understand how to use it. Here is a classic type of image that shows what Bilateral Blur is good for. I have very sharp objects here in terms of these wood pallets, the outlines around the headlights, the wheel wells etcetera. I also have several soft elements like this fog that the car is driving through. I'll select Car Through Fog and apply Effect > Blur & Sharpen > Bilateral Blur.
Now the first thing that happens is that the image goes somewhat monochromatic. That is the default setting for Bilateral Blur and probably is not what you want. You almost always want to enable Colorize which will bring back some of the original color in image. Now you will notice that sharp-edged objects like these pallets, the outlines around headlights, the wheels wells, etcetera have remained sharp but the fog has gone considerably softer. Off, on. The Radius parameter controls just how soft the fog is.
As I turn it down, you'll see I'm back to sharp image. So I turn it back up. I'm selectively softening the indistinct parts of the image while keeping my sharp edges. The Threshold determines where that line is between soft and sharp. I crank it up. You'll see that far more of the image is soft. If I reduce it down, you'll see that the whole image is sharp again. So it determines that threshold between soft and sharp images. Let's go and look at this with a few other images. Here I have a face and again this is something where I might want to keep some sharp details like the eyes, but soften other details. This is a de-interlaced video. I've got some trouble in the whiskers here. I've got some distracting things happening in the background, etcetera.
I'll select the lion. Apply Effect > Bilateral Blur. It's the most recent effect, so it's come at the top of the list. Turn on Colorize to get color back in the lion's face. You see again, I'm keeping some sharpness in the eyes. But I'm softening a lot of things that were happening with the fur and a little bit with what was going on in the background. I can play around with the Threshold and how much I'm blurring. This image, I probably want to blur a little bit less. Get a little bit more detail back into the face. But I might want to try up in the Threshold so I can blur more of the background image to go ahead and keep features such as the eyes, the mouth, the nostrils, etcetera. Playing around with a higher blur and a lower Threshold. Now I really got a lot more detail on the fur, because I've lowered the Threshold. I see there are fewer things that I want to blur but I still have some general softening going on in the image.
Let's look at the third example. Here is something that you think Bilateral Blur might be good at, but I have to give you cautionary tale. So I zoom in on this woman. You'll see that we've got some problems here in terms of lines around her eyes. We've also got this splotchiness caused by JPEG compression of this image. This is an image where we might say Smart Blur would be great. You want to keep the details in the eyes and the teeth but lose the splotchiness and lose the lines. Well, I've worked with this image earlier and I came to a determination that a small Radius with a slight blurring and a low Threshold kind of gave me what I wanted.
I'll turn on the effect. You'll notice my cursor takes little while to update before this image actually draws. This is the problem with Bilateral Blur. The smaller the details you try to make out, the longer it takes to calculate. Even in this case, I've got somewhat what I want. I still have the teeth, I still have the eyes but the skin has been softened. Go back to 100%, not too bad. But frankly, it's hard to get this subtle of an image with Bilateral Blur. If I am doing this type of image, instead I will use the Smart Blur effect, which renders a bit faster in these fine details and makes it easier to maintain details on the face and the eyes and the teeth.
Just keep in mind if this is the type of image you're going after, Bilateral Blur may not be your best solution. You might look at something else like Smart Blur. Finally, let's look at a creative application of Bilateral Blur. We've created entire training modules and what we call the Filmic Glow technique. The Filmic Glow is based on the idea of duplicating footage, applying some sort of blur effect to a copy of your footage. I'm turning Colorize back on and using a blend mode to mix that Colorize version back on top of the original.
As a result, you get more intense colors but you also get a bit of softening around the edges, a bit of a gentle blooming like slightly overexposed film. Here you can go ahead and crank up the Radius and really get some nice blooming and softening. Just to show you, this is without and with. You'll see it really helps get rid of some of the film grain that's in this footage and create some nice Filmic Glow to the overall result. So that's a nice creative application of Bilateral Blur. So to summarize, Bilateral Blur tries to keep details, by blurring soft areas in between those details. It's not so good when you're going for realistic things, such as just improving the look of someone's face, but it is good at impressionistic imagery or creating special effects such as a Filmic Glow sort of treatment.
After Effects gurus Chris and Trish Meyer share their real-world insight into how to get the most out of the effects that come bundled with this popular software. After Effects: Insight into Effects covers their favorite effects, hidden gems, optimal parameter ranges, "gotchas" to avoid, and alternative effects to consider. Among other tidbits, this course also contains "special topic" movies that pertain to more than one effect, demonstrate how to use After Effects more efficiently, and compare different effects to try in order to achieve a desired creative result. After Effects: Insight into Effects is recommended for all After Effects users, regardless of which version they use. This ongoing series that will be updated with new movies on a regular basis.
This course was recorded using After Effects CS4, but it contains many timeless concepts and effects. After Effects: Insight into Effects is recommended for all After Effects users, regardless of which version they use. This is an ongoing series that will be updated with new movies on a regular basis.