How To Defish The GoPro In FCP

    GoPros are awesome. Over the winter I use them on at least a weekly basis. They are great for sports and getting right up close to the action. The Fisheye lens on the GoPro is perfect for that, but what happens when you want a shot without the extreme barrel distortion?

   I have looked all over the internet for examples of how to do this and for the most part the tutorials require either a program I don't have, a plugin I don't want to pay for or it only will work for photographs. So here is a quick rundown on how to do some quick lens correction in Final Cut Pro.

Image size, image after pin-cushion and usable area.

   What helped me figure this one out was actually the articles on defishing photographs. A lot of them mentioned using a pin-cushion tool to pull the corners out. I started looking for a way to do this in FCP and found the Bulge tool could produce similar effects.

   First I imported the footage I wanted to use--a rotating time-lapse from the top of a fan gun at Pats Peak. Now hold on a second. I'm sure at this point you are saying to yourself, "Isn't a time-lapse just a series of photos? Didn't he say this was for video?" Yes you are correct but this method works for video too, the first step is just me converting the photos to a .MOV, so if you are just importing plain old video you can skip the next paragraph.

   Ok, I brought everything into Quicktime and exported my image sequence to Apple ProRes 422 (LT) as a 1920x1440 video, down-resed from its native 4:3 size of 2592x1944. Even though my timeline will be 1080x720 16:9 I still want my 4:3 image to better adjust where I want to crop and a better resolution to reduce artifacts and keep the picture as clear as possible.

And under motion tab: Scale 125

   Now we can take our footage and bring it into Final Cut. I apply the Bulge filter to my footage and then adjust it to make the corners pulled out as far as possible yet shrinking the video as little as possible (because having to zoom back into it will take away the sharpness of the overall image). I also included the Fisheye filter and gave it a negative value because I found Bulge tends to still have some slight distortion in the corners if used alone. See screencap for the settings I used (you can ignore the Flop filter just because I shot this upside down). If you look at the pole on the left side of the video in the viewer you can see how little distortion there is.

   This trick may take some tweaking and as long as you use the same size video throughout, this set of effects can be cut and pasted to other clips rather easily. And the great thing about this trick is you don't really loose all that much off the edges! Sure there comes render time but for a quick and easy lens correction for free with the tools you already have? Perfect.

EDIT: Here it is in the video I just posted!