So You Think You Want IMag?
By Michael Fay
IMag is an acronym that describes a functional capability within a live video production system. Image Magnification, to be specific, is the real-time reproduction and display of an enlarged image, as captured by one or more video cameras.
Within the range of the camera’s lenses, and the sufficiency of the lighting system, the enlarged image can include any of the various activities taking place on stage or elsewhere in a facility. In a House of Worship setting, the enlarged image is typically that of a leader or teacher while delivering a message or lesson.
The need for IMag capabilities most often becomes necessary in facilities that are quite large; so large that many of the seats in the room are too distant to allow a reasonably good view of the people and activities taking place on the stage or platform. One or more displays may be used. Both video projection and direct, flat-panel displays can work well in this application.
IMag presents significant technical challenges. When considering an IMag signal path, the video signal latency can easily become a problem if the signal path through-put timing (between the cameras, projectors and displays) is not kept to an absolute minimum. However, achieving this goal comes at a cost, which may become prohibitive for the Owner.
For IMag applications, the currently-accepted “standard” for maximum video latency is 7 video frames, or a total of 116.67ms when using a 60 fps refresh rate. 116.67ms is just a little over 1/10 of one second. Anything greater in length becomes obvious to the average viewer, and a distraction to the desired performance or presentation on stage.
Why the distraction? The presentation of the enlarged image can easily arrive too late, and is therefore not in sync with the live presentation or performance that is taking place right next to the large display(s).
In order to perform successfully, IMag systems require a very specific combination of hardware and software, as well as some skilled human interaction. Key elements include, but are not limited to:
IMag may sound like a nice idea but it is fraught with technical, operational and financial obstacles. If you are facing the IMag challenge alone, we would like to help. Our best results start with a conversation that outlines the needs, constraints and goals for your new systems.
Michael Fay is General Manager of the Sound Image Contracting Division; an audio, video and acoustical systems designer; a member and graduate of multiple SynAudCon workshops; a member of the Acoustical Society of America; and former editor of Recording Engineer/Producer magazine.
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© Copyright Michael Fay 2011