Image restoration techniques in surveillance applications

So far we mentioned several important applications where image restoration techniques are valuable. One of them is definitely surveillance, but let’s clear up something at the beginning. When we are talking about surveillance we are not thinking on spying. Indeed spying is part of a surveillance, but only a small part. Surveillance is important as an infallible part of the protection of the people and properties. It is part of the traffic control and safety, law enforcement, forensic, environmental protection (like wildlife monitoring) and of course military. Here we are only focused on video (or image) based surveillance.

Let start with mentioning several very important problems that restoration techniques are trying to solve:

• Video/Image blurred due to motion of the vehicle or/and people (and camera)

It is clear that, for example, in video surveillance of vehicles the very subject of interest (vehicle) is moving and additionally camera can move due to the influence of wind or vibration. All these movements can cause the blur effect in video, so-called, motion blur. In many cases, because of the motion blur, we are not able to detect the subject of interest correctly, for example, we are not able to read numbers and letters on the car plate. Here we can use deblurring techniques to restore this video and for example, read car plates.

Blurred and deblurred car plates [1]

• Video/Image noisy and/or blurred due to equipment used

Here we are talking about videos (and images) noisy and/or blurred due to equipment used for filming. We all know that a good equipment is expensive and that a cheaper one sometimes is not giving the desired result. Here again, we can combine the equipment that we have with restoration (denoising and deblurring) techniques.

Corrupted and denoised video [2]

• Extreme zoom surveillance (astronomy and wildlife monitoring)

Applications of digital imaging with extreme zoom are traditionally found in astronomy and wildlife monitoring. For example, you want to film a wild animal during some sensitive moment, like feeding, but you can not come to close. Usually, in that situation, people use extreme zooming. You can imagine that video or image that you take (especially if you do not use a very good camera) will be nearly useless and again, here, image restoration methods can help.

Extreme zoomed image of face [3]

• Video/Image artefacts as result of the compression 

Here, we have a problem with lack of storage space. It is not hard to imagine that if we are taking hours and hours of videos, in one moment we will spend all our storage space. In some application, you can delete videos that are old several days, but what we can do if all our collected videos are precious and we can not delete them? In that case, you can use compression techniques to compress your videos so they take a less space. During compression, you will surely lose some information that maybe can be retrieved by using some of the video restoration methods.  

References:

[1] Svoboda, P., Hradis, M., Marsik, L., & Zemcik, P. (2016). CNN for license plate motion deblurring. arXiv preprint arXiv:1602.07873.

[2] V. Cheung, B. J. Frey, and N. Jojic.  Video epitomes.  Intern. Journal of Computer Vision (IJCV), 2007.

[3] Y. Yao, B.R. Abidi, M.A. Abidi. Extreme Zoom Surveillance: System Design and Image Restoration. Journal of Multimedia, 2007.