The Gaussian Blur effect blurs and softens the image and eliminates noise. Of all the blur effects, Gaussian Blur has the most simple user interface, which we will look at now.
To apply a Gaussian Blur, select your footage, then go to Effect, Blur and Sharpen, Gaussian Blur. There are only two properties to this effect: Blurriness and Blur Dimensions. The Blurriness value determines how blurry your image will become. As I’m sure you can figure out, the higher the value, the blurrier the image will be.
Blur Dimensions can be set to Horizontal and Vertical, only Horizontal, or only Vertical. The default is to blur in both axes.
The major disadvantage to the Gaussian Blur is the lack of a Repeat Edge Pixels option which is found in the Fast Blur. You may have noticed that as I increase the Blurriness, the edges of our image begin to fade away. But if we were to apply a Fast Blur instead, we can turn on the Repeat Edge Pixels property, which will preserve our edges. Because of this issue, I never use the Gaussian Blur effect. I recommend you stick with the Fast Blur.
The Gaussian Blur is obsolete, in After Effects anyway. I would actually be curious to hear what all of you have to say. Do you prefer the Gaussian Blur over the Fast Blur? Or do you also think it is outdated?
Before I wrap things up, I wanted to mention a technique I often couple with my blurs. I will duplicate my footage, apply my blur, and then I’ll change the transfer mode as well as the opacity of the duplicated layer. By changing the blur amount, you can get a lot of different interesting looks.