Those of you who track me on Facebook or LinkedIn will have noticed I’m now listed as Founder & CTO of Fabl Video Ltd. So what is this company and what does it do? If you’re impatient you can just go look at our first product, Reliv for GoPro for iOS on the App Store.
Fabl Video Ltd is a startup promoting some video processing technology we built. I think the technology is pretty cool, but why don’t I show you what it does and let you decide what you think?
The motivation for building the technology is the rise in popularity of wide-angle action cameras (for example the GoPro Hero, Contour Roam, etc, etc) which are popular for recording all kinds of outdoorsy fun. I bolted a GoPro camera to my road bike handlebars and here is what it looks like:
As you can see the view angle is very wide, which is great for capturing a lot of action but has the side-effect of making things look rather weird at the edges. For example if you watch a lamp-post it appears straight when it is in the centre of the picture and then curves dramatically as it approaches the edge of the frame.
It turns out the GoPro mode I used to film this, called Superview, exaggerates this bending effect by squashing the 1920×1440 pixel image from the sensor into a 1920×1080 pixel image in the video file. So the first part of our technology, fabl reverse superview, reverses this squashing effect to restore the original shape of the image as the camera sensor saw it:
As you can see things look a little more normal now, although lamp-posts still bend as they get to the edges of the frame. You could avoid this by shooting the footage with a rectilinear lens, but no action camera comes with a rectilinear lens (for the good reason that they are bulky, requiring more elements and groups than there is space for in a compact action-camera device). So the second part of our technology, fabl decurv, processes the captured footage to produce what would have been captured by a rectilinear lens in the same place:
As you can see the lamp-posts are now straight all the time. This is cool, but it still doesn’t look the way the real world looked when I was actually there. There are two reasons for this: human visual perception doesn’t have as wide a field-of-view as that image; and it is not normal to look exactly where the handlebars are pointed all of the time. So we enhanced fabl decurv to create fabl reliv, a technology which processes the curvilinear footage to produce what would have been captured by a zoomable and movable rectilinear lens in the same place. In other words it can make any shot which could have been seen by a motorised camera mounted in the same place you had mounted the wide-angle camera. I have used this technology to produce the ride as I remember riding it, by limiting the field-of-view to that of normal human perception and pointing the virtual camera in the directions that I remember looking as I was riding:
I hope you agree that’s pretty neat!
But there’s one more significant thing I haven’t told you yet: how long does this conversion process take? Obviously if it takes less than 1/30 of a second that opens a lot of possibilities for use with live video; but if it’s slower than that it would be limited to post-production workflows. I’m pleased to say that our technology is fast enough for live use even on relatively modest hardware: we have successfully processed 1080p HD video at 60fps on an iPad Air. If you want to try it for yourself you can pick up Reliv for GoPro for iOS on the App Store.