A bluffers guide to image stabilisation


Mike Colyer TV-Bay Magazine
Read ezine online

i

(Due to the number of image references this articleis best read via the digital magazine on the link above)

This month’s article is about Jelly. Unfortunately, not the kind that can be served with whipped cream after about four hours in the fridge (sorry) – but instead the video artefact seen from improperly stabilised video cameras.

One of the greatest challenges I face when designing a Special Camera system is how to minimise such vibrations, be they the very passive – such as vibrations from a human wearing a camera system (10 – 20Hz), or more pronounced (try strapping a camera to a race car!).

Many small cameras (including mobile phones) now boast they use Electronic Image Stabilisation (EIS) or Optical Image Stabilisation (OIS) to combat this. In this article, we’ll explore both of the technologies and how picking either one may affect your shoot.

Firstly, Optical Image Stabilisation. OIS uses mechanics in order to perform image stabilisation. This is performed by either shifting the lens, a part of the lens, the sensor – or all of the above. Figure One shows a lens-based OIS implementation. In such an implementation, gyroscopic sensors will feed values measuring lens position in regards to pitch and yaw (as per Figure Two) to a microprocessor. Once the on-board processor has calculated how much displacement has occurred, either magnets or small pouches of fluid are triggered to move the lens in the opposing direction to the movement the camera experienced. In this case, in Figure One, the shifting lens would move up, down, left or right based on this information. This means that the unstable image path entering the lens is compensated for by the motion of the shifting lens, thus meaning the sensor receives a stabilised image.

The alternative approach is to employ EIS, or Electronic Image Stabilising. This method makes no attempt to mechanically stabilise the image, instead relying on in-camera software to interpolate the motion the camera’s gyros have noted, then digitally make corrections based on this.

The first picture shows a camera’s sensor running normally, using the full sensor for active imaging. The second cell shows what happens when EIS is turned on – the image becomes cropped to permit some pixels to be used as ‘buffer’ to provide stabilisation. The final cell shows what happens when the gyros detected that the camera’s lens has pitched up – it has compensated by using a lower section of the sensor for the active image, now turning the upper area of the sensor into unused, buffer pixels.

There is no ‘better’ technology – however, I tend to consider a few things before selecting which approach I wish to use.

Firstly, OIS has the disadvantage that systems tend to be slightly larger with a higher cost. If it is expected the camera could be damaged or needs to be kept small, it can sometimes be hard to justify the additional bulk or price for a camera that may only ever be used once! In addition to this, having additional moving elements does, in some cases, reduce how robust the system is.

However, EIS in many cases reduces the overall resolution of the image to provide the needed buffer space for the image stabilisation. Also, as no attempt to stabilise the image has been made, motion blur can sometimes be more pronounced as the image being captured by the sensor is less stable.

For now, it remains a balancing act when it comes to selecting how best to stabilise a camera. Of course, no solution is better than a properly mounted rig – yet I’ll be looking around IBC this year with keen eyes to see how manufacturers have developed on their stabilisation techniques.


Tags: iss127 | stabilisation | eis | ois | Mike Colyer
Contributing Author Mike Colyer

Read this article in the tv-bay digital magazine
Article Copyright tv-bay limited. All trademarks recognised.
Reproduction of the content strictly prohibited without written consent.

Related Interviews
  • BeyondHD - Letus Helix Gimbal System at BVE 2015

    BeyondHD - Letus Helix Gimbal System at BVE 2015

  • Memory Mic from Sennheiser shown at IBC 2018

    Memory Mic from Sennheiser shown at IBC 2018

  • Sennheiser iPhone Microphones at IBC 2107

    Sennheiser iPhone Microphones at IBC 2107

  • Sennheiser HandMic digital and MKE 440 at IBC 2016

    Sennheiser HandMic digital and MKE 440 at IBC 2016

  • Sennheiser VR at IBC 2016

    Sennheiser VR at IBC 2016

  • Zeiss at BVE 2016

    Zeiss at BVE 2016

  • Sennheiser HDM Pro at BVE 2014

    Sennheiser HDM Pro at BVE 2014

  • Carl Zeiss on BroadcastShow LIVE at IBC 2013

    Carl Zeiss on BroadcastShow LIVE at IBC 2013

  • Sennheiser at BVE 2012

    Sennheiser at BVE 2012

  • Sennheiser at BVE North 2011

    Sennheiser at BVE North 2011

  • KitPlus filming rig used at NAB 2017

    KitPlus filming rig used at NAB 2017

  • KitPlus filming rig used at BVE 2017

    KitPlus filming rig used at BVE 2017

  • Kit Overview from IBC 2015

    Kit Overview from IBC 2015

  • Blackmagic Design at NAB 2012

    Blackmagic Design at NAB 2012

  • Pinknoise at BVE North 2012

    Pinknoise at BVE North 2012

  • Viaccess-Orca at IBC 2014

    Viaccess-Orca at IBC 2014

  • Digital Vision on BroadcastShow LIVE at IBC 2013

    Digital Vision on BroadcastShow LIVE at IBC 2013


Related Shows
  • Zeiss at BVE with Den Lennie

    Zeiss at BVE with Den Lennie


Articles
AI in Media and Entertainment
David Candler Artificial Intelligence (AI) is a term appearing everywhere these days. What is happening in media and entertainment (M&E) that makes the industry ripe for AI? In other words, why does the M&E industry need AI?
Tags: iss134 | AI | wazee | David Candler
Contributing Author David Candler Click to read or download PDF
An Obituary to Timecode
Bruce Devlin - new A stoic and persistent character that stubbornly refused to change with the times, Timecode has finally passed on, but no-one has noticed. A long-lasting industry veteran, Timecode was brought into this world at an uncertain date in the late 1960s due to the needs of analogue tape workflows and the demand for synchronisation between audio and video devices. A joint activity between SMPTE and the EBU led to the work on Time and Control codes starting its journey to standardisation in the early 1970s.
Tags: iss134 | timecode | smpte | ebu | edit | Bruce Devlin - new
Contributing Author Bruce Devlin - new Click to read
Giving Welsh sport a global audience
Adam Amor From the Ospreys Rugby Union team, to the Football Association of Wales, as well as national cycling, swimming and boxing coverage, Port Talbot based Buffoon Film and Media has been heavily involved in putting Welsh sports on the world stage.
Tags: iss134 | blackmagic | atem | buffoon | micro studio camera | Adam Amor
Contributing Author Adam Amor Click to read or download PDF
Keeping it remotely real
Reuben Such Everyone wants to do more with less. Always have, although it could be argued that doing more with more is something to aspire to, not many have that luxury. So let’s stick with the prevailing winds of doing more with less, and not just doing more, but doing it remotely, particularly in terms of production. Remote production, in particular, is getting a lot of attention in the field these days, but not so much in terms of the remote operation of fixed studios.
Tags: iss134 | remote control | IPE | IDS | Reuben Such
Contributing Author Reuben Such Click to read or download PDF
Accelerated Workflows with eGPU
Mike Griggs From the UK’s National Trust to magazine publishers to manufacturers, digital content creator Mike Griggs has a wide and varied portfolio of clients for whom he creates 3D art, motion graphics and multimedia exhibits. A typical day might involve sampling birdsong near Virginia Woolf’s country estate or creating 3D animations for VR. To keep on top of these demands, Griggs wanted to take the full power of the GPU computing revolution on the road.
Tags: iss134 | sonnet | egpu | amd | post production | editing | Mike Griggs
Contributing Author Mike Griggs Click to read or download PDF