Image sensors evolve to meet emerging embedded vision needs - Part 1

Brian Dipert, Editor-In-Chief, Embedded Vision Alliance and Eric Gregori and Shehrzad Qureshi, Senior Engineers, BDTI -June 13, 2012


In Part 2, "HDR processing for embedded vision," by Michael Tusch of Apical Limited, an EVA member, we discuss the dynamic range potential of image sensors, and the various technologies being employed to extend the raw image capture capability.

Look at the systems you're designing, or more generally at the devices that surround your life, and you're likely to see a camera or few staring back at you. Image sensors and their paired image processors are becoming an increasingly common presence in a diversity of electronic products. It's nearly impossible to purchase a laptop computer without a bezel-mount camera, for example, and an increasing percentage of all-in-one desktop PCs, dedicated computer displays and even televisions are now also including them.

Smartphones and tablets frequently feature image sensors, too, often located on both the front and back panels, and sometimes even arranged in "stereo" configurations for 3-D image capture purposes. And you'll even find cameras embedded in portable multimedia players and mounted in cars, among myriad other examples.

Application abundance
The fundamental justification for including the camera(s) in the design is often for elementary image capture purposes, notably still photography, videography, and videoconferencing. However, given that the imaging building blocks are already in place, trendsetting software and system developers are also leveraging them for more evolved purposes, not only capturing images but also discerning meaning from the content and taking appropriate action in response to the interpreted information.

In the just-mentioned vehicle case study, for example, an advanced analytics system doesn't just "dumbly" display the rear-view camera's captured video feed on a LCD but also warns the driver if an object is detected behind the vehicle, even going so far (in advanced implementations) as to slam on the brakes to preclude impact.

Additional cameras, mounted both inside the vehicle and in various locations around it, alert the driver to (and, in advanced implementations, take active measures to avoid) unintended lane transitions and collisions with objects ahead, as well as to discern road signs' meanings and consequently warn the driver of excessive speed and potentially dangerous roadway conditions. And they can minimize distraction by enabling gesture-interface control of the radio and other vehicle subsystems, as well as to snap the driver back to full attention if he or she is distracted by a text message or other task that has redirected eyeballs from the road, or has dozed off.

In smartphones, tablets, computers and televisions, front-mounted image sensors are now being employed for diverse purposes. They can advise if you're sitting too close or too far away from a display and if your posture is poor, as well as preventing extinguish of the backlight for as long as they sense you're still sitting in front of them (and conversely auto-powering down the display once you've left). Gesture interfaces play an increasingly important role in these and other consumer electronics applications such as game consoles, supplementing (if not supplanting) traditional button and key presses, trackpad and mouse swipes and clicks, and the like.

A forward-facing camera can monitor your respiration (by measuring the chest rise-and-fall cadence) and heart rate (by detecting the minute cyclical face color variance caused by blood flow), as well as advise if it thinks you've had too much to drink (by monitoring eyeball drift). It can also uniquely identify you, automatically logging you in to a system when you appear in front of it and loading account-specific programs and settings. Meanwhile, a rear-mount camera can employ augmented reality to supplement the conventional view of an object or scene with additional information.

These are all examples of embedded vision, a burgeoning application category that also extends to dedicated-function devices such as surveillance systems of numerous types, and manufacturing line inspection equipment. In some cases, computers running PC operating systems historically handled the vision analytics task; this was a costly, bulky, high power and unreliable approach. In other situations, for any or all of these reasons, it has been inherently impractical to implement vision functionality.

Nowadays, however, the increased performance, decreased cost and reduced power consumption of processors, image sensors, memories and other semiconductor devices has led to embedded vision capabilities being evaluated in a diversity of system form factors and price points. But it's also led to the need for increasingly robust imaging subsystems (see sidebar "Focus: the fourth dimension").

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