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Sony’s View-DR Wide Dynamic Range Technology – What is it? (with videos)

Sony View-DR plus screenshotsSony’s entire top-of-the-line network camera range features a system called View-DR. Billed by Sony as “Brilliant clarity even with strong backlighting” it’s designed to surpass conventional wide dynamic range (WDR) systems, improving the visibility of subjects in high-contrast lighting or back-lit areas.

It does this using a technique called ‘multi-frame imaging’ by serially capturing up to 120 frames each second at different exposure times, then combining a subset of them together to form the final image, resulting, after some algorithmic image processing magic, in a best-in-class wide dynamic range.

So how does this feature differ from conventional wide dynamic range systems as used by some other camera manufacturers, and how effective is it?

What is a camera’s dynamic range?

We recently explained in depth the limitations of IP cameras in strong lighting in our evaluation of the Axis P3384-V. Much like your eyes, the sensors on network-based security cameras take in a limited amount of light in any one moment. This is referred to as the dynamic range. And, the dynamic range of most surveillance cameras is lower than the dynamic range of most scenes they overview, so they need to get clever to overcome this.

For example, if you use a camera to cover a room with a window at the far point, objects outside will be too bright to see – outside the camera’s dynamic range – if the room itself was exposed correctly. The same is true for the room’s dark shadows as these will be below the camera’s dynamic range.

In areas with high contrast lighting, this results in blindspots throughout your scene and where goings-on cannot be monitored. For security installations, this is far from optimal.

How conventional wide dynamic range software works

Conventional wide dynamic range implementations, those that don’t use the now more common multi-frame image processing, such as those in cameras from Panasonic, earlier Sony cameras (such as the excellent value SNC-EP521) and some older cameras by Axis and other manufacturers, used software to amplify the available light in dark areas and limit brightness in over-exposed areas. As a result, the dynamic range is made wider, but the effects and visual gains are limited.

The maximum and minimum light sensitivity of the camera is the limiting factor. The software makes improvements on both the dark and the bright sections, but if detail is whited-out or blacked-out, it is lost. This conventional WDR software is handy for edge cases, where the detail is just visible, but in light levels beyond this, the data is irretrievable.

Sony’s alternative method for WDR – View-DR

Sony’s View-DR system takes a different approach. Instead of taking a single image of the scene, it takes multiple images with different exposures. Brightly lit areas will be correctly exposed in images with short exposure, while darker areas will be captured in longer exposure shots.

A visual representation of Sony's View-DR and Exmor technology

Individually, these images wouldn’t be too useful. Each image would have areas that are perfectly exposed, with the rest being either over- or under-exposed. View-DR takes these images, ignores the sections that are incorrectly exposed, and combines the remaining images into a single frame. The result is a huge gain in dynamic range, with all areas of the image correctly exposed.

Below we have demonstration to show the difference that View-DR can make to a typical scene.

In this scene we have a dark indoor environment with an upper-level foyer lit by sunlight. You’ll see that the camera’s exposure is ensuring that detail can be seen in the lower level, but this in turn has made the upper foyer and entrance-way over-exposed. Additionally, we can see nothing outside the doors and details in the darker areas are difficult to make out.

The same scene with View-DR enabled:

We can see now that the foyer is much clearer. We can see far more detail than before and importantly, the scene outside is visible. On top of this, the visibility of darker areas is also increased. In the far left, the person sitting on the bench, who we may previously have missed, is now more distinguishable and in this scenario would not be missed.

The benefits of View-DR are real and tangible

The benefits here, like the WDR-corrected images, are clear. In security there are no second chances, and things that happen in areas you can’t see won’t be repeated. It is important to catch all actions in the camera’s field of view, so effective wide dynamic range technology like View-DR has a direct and consequential impact on the effectiveness of a network-based CCTV system.

In the case of the footage above, the addition of View-DR on the scene greatly improves the chances of subject detection, increases the effective range for Sony’s DEPA analytics and provides more positional awareness for any operator monitoring the scene. Similarly, footage retrieved after any security breach will reveal more visual information.

View our range of Sony IP cameras with View-DR built in or leave us a comment below on your experience with View-DR, or any WDR-enabled camera.

Published on January 29th, 2013 by Kevin Bowyer

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