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...

Chris Brown Discusses The Themes Of The 2024 NAB Show

The Broadcast Bridge sat down with Chris Brown, executive vice president and managing director, NAB Global Connections and Events to discuss this year’s gathering April 13-17 (show floor open April 14-17) and how the industry looks to the show e…

Standards: Part 4 - Standards For Media Container Files

This article describes the various codecs in common use and their symbiotic relationship to the media container files which are essential when it comes to packaging the resulting content for storage or delivery.

Standards: Appendix E - File Extensions Vs. Container Formats

This list of file container formats and their extensions is not exhaustive but it does describe the important ones whose standards are in everyday use in a broadcasting environment.

System Showcase: Delivering 175 Camera Production For The Repco Supercars ‘Bathurst 1000’

The Bathurst 1000 is a massive production by anybody’s standards, with 175 cameras, 10 OB’s, 250 crew and 31 miles of fiber cable. Here is how the team at Gravity Media Australia pull it off.

Standards: Part 3 - Standards For Video Coding

This article gives an overview of the various codec specifications currently in use. ISO and non-ISO standards will be covered alongside SMPTE 2110 elements to contextualize all the different video coding standard alternatives and their comparative efficiency - all of which…