Image acquisition for live broadcast applications faces many challenges in a multiformat landscape. The increase in spatial resolution required by 4K UHD, in combination with the additional requirements of UHD standards, including a potential increase in frame rate and high dynamic range with good sensitivity and S/N ratio will require some compromises and design decisions on the part of manufacturers, and camera selection on the part of camera users.
It Comes Down to Selecting the Right Tool for the Right Job.
Some of these new requirements, especially increased resolution, have a negative impact on some important image parameters, such as sensitivity, noise performance and dynamic range. Multiple flexible solutions can address these challenges, including native format switching.
It All Starts with Pixels
Higher pixel count on a given imager size, means smaller pixels. Smaller pixels mean lower sensitivity and dynamic range. In other words, despite the apparent benefit of having MORE pixels when capturing content in native 4K, it may not always be ideal. The increased sensitivity of the larger pixels captured using full HD imagers is sometimes preferable.
Why is There Not One Solution for All the Challenges?
All current UHD image solutions have strengths and limitations:
- Solutions with large imagers address the specific requirements of digital cinematography applications shallow depth of field is great for film production, but not for live production which requires the highest performing optics
- Solutions with 2/3" B4 lenses address the specific requirements of most live applications large depth of field, captures fast moving objects, largest zoom ranges required for most sport applications, compact lenses and high sensitivity
Today's technology does not offer native 4K imaging that delivers the same performance in terms of sensitivity as the best HD cameras available. In addition, native 4K acquisition with 2/3" imagers does not offer global shutter operation a requirement in many of the more demanding applications with high speed movement. Another complication some limitations are optical, and not solvable. HD will be used for many years. Most equipment purchased today will need to be used for both 4K UHD and HD. For now, mixed simultaneous operation might be the best option.
And the questions don't stop there. There's also a decision to be made with regard to 4K UHD transport Quad-SDI or IP. More on that in a future post!