Nokia has emphasized following two aspects of imaging in what they call as “PureView Phase 2” on Lumia 920.
- Benchmark low light performance
- Steady video in all lighting conditions
Now have a look at following picture posted by Anandtech in Lumia 920’s hands-on from yesterday’s event.
Anandtech explains about the above image.
Nokia had a scene setup in the dark to test the Lumia 920’s low light camera performance. A vase with flowers was set inside a dark box with a port big enough for you to get a smartphone inside. Without using a flash or a tripod, low light performance of the 920 was pretty impressive.
It is rightly said a picture is better than thousand words. iPhone 4S was not able to even detect the flower vase in above comparison and Lumia 920 presents a full good-looking picture of Flower base. Amazing, isn’t it ?
Nokia is certainly going to set a benchmark in low-light imaging with Lumia 920’s pureview camera it seems!!
Now let see how Nokia explains this great low-light performance.
- Next Generation Back Side illuminated sensor (BSI). BSI sensors use a reversed structure, so the wires and metal are in the base of the sensor and the photosensitive diodes are directly below the micro lenses and colour filters. This results in more photons reaching the photosensitive diodes [pixels] and therefore superior pixel performance, most notably in low light.
- Wider Aperture F2.0 for getting more light in. Nokia used sensors are at least 10% larger than comparable sensors of the same resolution to accommodate the true 16:9 aspect ratio, this was even more of an optical design achievement than other cameras with a smaller sensor area.
- Optical Image Stabilisation (OIS). OIS works by detecting camera movement using a gyroscope – a highly accurate sensor used to detect the degree and direction of movement. Rather than a single lens element being shifted to compensate for camera shake, Nokia’s OIS system moves the entire optical assembly in perfect synchronisation with the camera movement, or to be more precise, unintended camera shake. The benefit of this approach is that the amount and form of camera movement that can be compensated for is much greater.
Adding up all of the advantages of Nokia’s OIS system means camera shake in lower light can be compensated for to lower lighting levels than conventional OIS systems, ultimately resulting in low light photography. Check the graph below which shows how OIS ( the orange line) helps in maintaining Image sharpness.
Now coming to second aspect of the PureView on Lumia 920, which is Steady video in all lighting conditions, let see how Nokia explains that.
- The advantages of OIS are not constrained to just still images in low light. OIS can also help provide one-handed usage. Sometimes capturing pictures or video one handed is more convenient and natural. However, even in reasonable lighting, this typically results in camera shake. This really helps to extend the spontaneous use of smartphones as a modern method of capturing moments as they occur during everyday life.
- By detecting the different movements the OIS system is able to compensate for unintended movement rather than intended movements e.g. panning. One of the most important aspects of good smartphone video recording is smooth recording. Capturing smooth video whilst moving can be extremely difficult. Even ensuring small movements are unnoticeable during playback can require constant concentration. This often results in video recording becoming tiring, other than for the shortest of video clips. In addition, for the individual who’s recording it, it detaches them from the ‘live’ action as they concentrate continuously on the viewfinder. When capturing video OIS works slightly differently to when capturing stills.
Other major improvements are also there which add to overall performance of the Camera.
- Next Generation Dual LED flash with a pulse flash burst. This provides a similar capability to xenon flash where the flash fires a short single flash of light. This flash is short enough in duration to effectively freeze subject movement. Whilst the duration of the flash is still not as short as a xenon flash, it is short enough to provide a sharper picture of moving subjects than conventional LED’s which provide no such benefit.
- Nokia Image processing Technology. One of the most important new algorithms is our new denoise algorithm for reducing visual noise, which helps to further improve low light performance while keeping the image very natural. In the beginning of the project, we set ourselves a challenging target to create a product with the best low light performance ever in a smartphone, even in natural light. Every single part of the system was pushed for this goal: large aperture, new image sensor technology, optical image stabilizer and new image processing algorithms. When the technologies are combined, the improvements add up, and finally we have the results in our hand.
You can read the full PureView White Paper here.