Finally, the user’s vision also impacts the perceived image quality, as well as the required viewing distance of mobile devices. It’s no accident that Apple’s “retina” display can deliver images perceived as high quality. With its 326 PPI display, the iPhone 4S has a pixel density 14% better than the 286 PPI required to deliver a resolution compatible with a 20/20 visual acuity from a distance of 1 foot (see Chart 3, Maximum Visible PPI Related to Viewing Distance-Inch).
If the user’s vision is impaired, the required distance for maximum visible PPI decreases.
Yet, with these factors considered, if the user’s vision and device have the capability of interpreting and rendering HDTV video content and the network has the capacity, the mobile application should take full advantage of the HDTV network video source. And the future possibilities of enabling full-HDTV mobile usage in surveillance are growing stronger thanks to additional outside forces.
Industry advancements, policy-making agencies and the executive branch will significantly impact video mobility in public safety. The Presidential Executive Order (EO) recently released, “Executive Order—Assignment of National Security and Emergency Preparedness Communications Functions,” is significant:
“The Federal Government must have the ability to communicate at all times and under all circumstances to carry out its most critical and time sensitive missions. Survivable, resilient, enduring, and effective communications, both domestic and international, are essential to enable the executive branch to communicate within itself and with: the legislative and judicial branches; State, local, territorial and tribal governments; private sector entities; and the public, allies, and other nations. Such communications must be possible under all circumstances to ensure national security, effectively manage emergencies, and improve national resilience.”
Simply put, the National Broadband Plan (http://www.broadband.gov/plan/), which incorporates key technologies like LTE (Long-Term Evolution), will be expanded, standardized and managed to improve national security. With this EO, performance and dedicated spectrum needed to improve security data and video communications will be a reality in coming years.