Gyro, Distortion Correction, and FOV

Gyro, Distortion Correction, and FOV

September 27, 2017 Forums, M20, News, SJCAM SJ4000 Series, SJCAM SJ5000 Series, SJCAM SJ6 Legend, SJCAM SJ7 Star

Gyro Stabilization, Distortion Correction, and FOV (Field Of View) are three things most people get confused about for usage.

Most cameras of today have some version of these features, including that of smartphones, which are undoubtedly catching up fast with pro-level cameras.
Some of the things that many people ask about are how they correlate to each other since they don’t exactly line up when those functions are used.
So why can’t you activate all of them at once?
Let’s see if we can explain them to you in the simplest way possible, without getting too technical or too much into details.

Here goes…

Gyro Stabilization, AKA “EIS” or Electronic Image Stabilization, Anti-Shake.

This is a method of making the video less shakey. If you’ve ever seen the “Blair Witch” movie, yeah, plenty of the footages used are so shakey it’s almost vertigo-inducing, and most of the times (if not always) difficult to watch. Well, they’re made that way on purpose. And that’s the complete opposite of what Gyro Stabilization does.

Note: The other version of image stabilization is OIS (Optical Image Stabilization) where the camera’s physical parts actually do the moving to correct motion. Currently not on any SJCAM models.

It works by cropping a portion of what the sensor “sees” and moves it around so that you only get the part that is stabilized, like this:

How electronic stabilization works

Here’s a comparison between a non-stabilized footage versus gyro-stabilized: SJCAM SJ6 Legend Gyro Image Stabilization Test


Distortion Correction

Distortion, in the field of photography, is something observed as either a bulging or squished effect in images. For SJCAM cameras, it is what appears like the image is viewed through a glass ball (AKA “Fisheye Effect”, Barrel Distortion). This is caused by trying to fit as much view of the scene into the lens tube and onto the camera’s sensor, and is very characteristic of action camera photography.

Distortion can be corrected digitally through the camera’s processor in real-time, or much later, through post-processing using a computer.

Here’s how it is done:

How distortion correction works

 

Here it is in action: SJCAM M20 Fisheye Distortion Correction Test 2K@30fps

FOV or “Field Of View”

Everything that is included in the recording, which is either everything within sight of the sensor, or, just a selected portion of it (crop).
If you change to a narrower FOV, the camera will  just crop a portion of the whole frame, and show that part on the recorded image.

As seen in sample below:

How FOV works

 

And again in action: SJCAM M20 FOV Settings 2K@30fps


Wait, isn’t that like Digital Zoom?

Yea, it’s pretty much the same. Reason why I didn’t mention it in the title is that it is essentially the FOV function described above. Unlike optical zoom, which has moving physical parts to control how light refracts in the lens to get “closer” to the subject, digital zoom is a real-time variable crop of the actual image seen by your camera’s sensor.  The resolution stays the same, just that the sensor’s pixels are blown up to fill the image for recording.

Okay, now what?

Now, since these 3 highly helpful image manipulation techniques are in some form or another a “crop” of the original image that the sensor registers, current technology can only effectively process only one, or at most, two, at the same time. This is the same reason why in the menus you will see some of these features greyed out: they just can’t co-exist well for the reasons shown above. It’s like asking for someone to dance, and not move at the same time.

Perhaps in the future we might get all three functioning all at the same given instance (4, if you include digital zoom), but until then, you will have to choose which one you want to prioritize and choose that feature for your purpose.

Hope that this has enlightened you about how those 3 are related. If you have questions, please head over to the community forums and post them there. We would love to hear from you, join us THERE now!

-TF

Photo credits go to Jomarie Luistro of SJCAM Users Philippines Facebook Group
Video samples provided by Paul Anca of the TechTronic9000 YouTube Channel
BIG THANK YOU FOR BEING THE AWESOME PEOPLE THAT YOU ARE!