There Is A Need For Realtime Lens Distortion And Perspective Correction

The ever-increasing use of small broadcast quality HD cameras with wide angle or fisheye lenses have become increasingly prevalent. Their use can be found in live broadcast applications such as sport, ENG, wildlife programming, and reality TV, with non-broadcast use in medical, forensics/security and online gaming.

However, the “fish eye’ effect associated with these extreme lenses is not well received by the content viewer or programme maker.

This lens distortion and curvilinear perspective errors arising from the use of these camera lenses, as well as the physical camera positioning can produce results which can be considered undesirable and require correction.

How can you correct these errors? For live image feeds, any rendered software based offline processing is not practicable, and any correction process must be easy to use in a real time environment.

Software? Hardware?

Software processes require rendering of images, an offline process, so such solutions do not work in real time with live streams – crucial for sport applications for example (for forensic/security and reality TV applications that do not require real time solutions, software based processes may be useful).

(Left) Pre corrected live feed showing classic lens distortion & curvilinear perspective artefacts and (Right) corrected live feed with lens distortion & curvilinear perspective artefacts removed.

(Left) Pre corrected live feed showing classic lens distortion & curvilinear perspective artefacts and (Right) corrected live feed with lens distortion & curvilinear perspective artefacts removed.

For real time use, a hardware solution is more appropriate. Employing a hardware-based sub pixel geometry engine, this corrects the lens distortions in real-time, and most importantly, does not add any visible artefacts to the corrected output. This geometry engine concept allows for correction of lens aberrations through the range of operational HD resolutions, making it useful for a broad range of media applications.

The technology does not require co-location with the camera source. The unit can be located remotely via industry standard 3G co-axial cable subject to commensurate distance limits, but optionally supports fibre connections up to and beyond distances of 1000 metres. The unit has a Genlock input removing the need for external Genlock/Synchroniser hardware too. The setup can be done via USB connection to a Mac or Windows platform.

System overview of the lens correction Geometry Engine – graphic courtesy AlphaEye.tv

System overview of the lens correction Geometry Engine – graphic courtesy AlphaEye.tv

The image correction parameters include zoom, rotate, X and Y axis tilt, as well as offset, and adjusting of the strength of ‘barrel’ distortion correction required to the image.

You might also like...

Designing IP Broadcast Systems: Where Broadcast Meets IT

Broadcast and IT engineers have historically approached their professions from two different places, but as technology is more reliable, they are moving closer.

Comms In Hybrid SDI - IP - Cloud Systems - Part 2

We continue our examination of the demands placed on hybrid, distributed comms systems and the practical requirements for connectivity, transport and functionality.

Wi-Fi Gets Wider With Wi-Fi 7

The last 56k dialup modem I bought in 1998 cost more than double the price of a 28k modem, and the double bandwidth was worth the extra money. New Wi-Fi 7 devices are similarly premium-priced because early adaptation of leading-edge new technology…

NAB Show 2024 BEIT Sessions Part 2: New Broadcast Technologies

The most tightly focused and fresh technical information for TV engineers at the NAB Show will be analyzed, discussed, and explained during the four days of BEIT sessions. It’s the best opportunity on Earth to learn from and question i…

Standards: Part 6 - About The ISO 14496 – MPEG-4 Standard

This article describes the various parts of the MPEG-4 standard and discusses how it is much more than a video codec. MPEG-4 describes a sophisticated interactive multimedia platform for deployment on digital TV and the Internet.