Dear Amped Tip Tuesday fellows – welcome to this week’s Tip! Today we will show you how a very simple tool, the Reverse filter, can boost your results significantly. Ok, I can hear you say: “Oh dear, how will these Amped guys fill a Tip Tuesday with such a trivial filter?”. Keep reading and you’ll find out!
The Amped FIVE‘s Reverse filter does something pretty straightforward: it reverses the order of frames. Since this is something that affects the way frames are presented, you’ll find this filter under the Presentation category. But not just there! There is another place where the Reverse filter is cited, that is, in the “hint” message of the Perspective Stabilization filter, as we show below:
What does that advice mean, and why is it there? To reason about it, let’s use a practical example: we are asked to enhance the license plate from these frames:
We are just in a case where the vehicle approaches the camera instead of moving away. Since the car is steering, we also have a significant change in the perspective of its license plate. Luckily, since Rev. 12727, Amped FIVE features the mighty Perspective Stabilization and Perspective Super Resolution filters, which will do most of the job for us. (If you haven’t updated to this release yet, don’t delay, update today! If you need to extend your Software Maintainance and Support (SMS) you can contact our local distributor or contact us).
What the Perspective Stabilization filter does is to register the perspective of all frames of the video over the first frame, to allow the following Perspective Super Resolution filter to properly merge information from aligned pictures (you may also combine information using the good old Frame Averaging filter). Now, when the vehicle is approaching the camera, the first frame of the video is the one where the license plate is farthest! Does it make sense to map all subsequent images to the smallest one? Not really. And it makes a difference.
Let’s assume that, because we are in a hurry, we decided to ignore the Perspective Stabilization filter advice, and thus simply selected the license plate in the first frame of the video:
After applying Perspective Stabilization, Perspective Super Resolution, and some Sharpening, we obtain this image:
Good, but not awesome… Instead, if we duly follow the advice and reverse the video, we can select the license plate from the “new first” frame, which is much more advantageous even at first sight:
And this is the final result after applying Perspective Stabilization, Optical Deblurring (we did not use it previously because it gave no advantage) and some Sharpening and Levels:
Much, much better! After finishing, I usually like to use the Compare Original filter to see the result of my work next to the original pixels… quite gratifying, in this case!
Just a side note: proper use of the Reverse filter does not benefit only the Perspective Stabilization filter, but all filters that register video frames over the first one; for example, the “manual” Perspective Registration also works this way.
This week’s takeaway is: sometimes simple things matter! Within Amped FIVE, even the simplest filter has its role in achieving the excellent results we would love you to reach.
That’s all for today! We hope you’ve found this issue of the Video Evidence Pitfalls series interesting and useful! Stay tuned and don’t miss the next ones. You can also follow us on LinkedIn, YouTube, Twitter, and Facebook: we’ll post a link to every new tip so you won’t miss any!