PureView Phase 2 – White Paper, Optical Image Stabilisation Floating Lens Explained.

| September 5, 2012 | 18 Replies

PureView seems to be quite complicated stuff. Remember the sweeping dismissal by folks who did not understand it, only to eat their words once they saw PureView eat their digital cameras?

A white paper was published explaining PureView Pro. Still a rather lengthy document for news and some publishers, but useful for those who were going around trying to reeducate those that Nokia had failed to teach properly in their own keynote.

Here is a document explaining Phase 2 – optical image stabilisation with the Nokia floating lens.

I’m just about to read it now, I’ve highlighted some initial interesting things but I’ll revisit this again later. There’s too much information to be condensed quickly.

I don’t understand how Nokia has this level of understanding of their product yet does not talk about something as important as this in their own keynote. Some conspiracy theories flying around thought they did this with PureView the first time because 808 was Symbian. No. Not at all. Nokia just plain sucks at presentation. Which is a shame given how awesome the first video was with the deconstructed 920.

PureView Phase 1:

Key benefits:
ï‚· Benchmark image/video sharpness
ï‚· Lossless zoom in stills and HD video
Key Technologies:
High performance sensor:
ï‚· True 16:9/4:3 aspect ratios
 Large 1/1.2” 41mp sensor
High performance Carl Zeiss
ï‚· High resolving capability
 Super wide-angle: 26mm – 16:9
ï‚· f/2.4 aperture
Advanced Image Processing:
ï‚· Pixel oversampling technologies
Powerful xenon flash + Single LED

PureView Phase 2:

Key benefits:
ï‚· Benchmark low light performance
ï‚· Steady video in all lighting
Key Technologies:
High performance sensor:
ï‚· True 16:9/4:3 aspect ratios
ï‚· Latest generation BSI sensor with
1.4 micron pixels
High performance Carl Zeiss
ï‚· Optical Image Stabiliser
 Super wide-angle: 26mm – 16:9
ï‚· f/2.0 aperture
Advanced Image Processing:
ï‚· Nokia image processing
Next generation high power/short
pulse LED flash

On the Xenon Flash: Pulse burst similar to xenon to freeze moving subjects.

Next generation LED flash
Whilst xenon, when married to a large capacitor, is perhaps the most powerful short
burst lighting source, the performance of LED’s have been increasing at a faster rate
than xenon and capacitor technologies. To bolster the low light performance, we’re
introducing a new generation LED. It provides the benefit of being able to be used as a
continuous light source e.g. for video or as a highly popular secondary function; a torch
and now for the first time – 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
Figure 1: The image circle and the 16:9 and 4:3 image areasnot 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

On image stabilisation.

But the most significant improvement comes from Optical Image Stabilisation (OIS). Yes
there are smartphones, which include digital stabilisation algorithms, and whilst they
have improved over time they are still far behind the possibilities of effective OIS
systems. Whilst digital cameras have incorporated OIS for a while, it’s virtually unheard
of in smartphones due to the various size constraints. OIS works by detecting camera
movement using a gyroscope – a highly accurate sensor used to detect the degree and
direction of movement. But that’s pretty much where the similarity between Nokia’s OIS
system and broadly comparable OIS systems ends.
In most OIS systems, a lens element moves in the opposite direction to the measured
device movement to compensate for unintended movement, effectively cancelling out
camera shake. This is a similar principle to the process of noise cancellation.
In itself, incorporating OIS in to a smartphone is challenging enough, but Nokia has been
successful in surpassing the typical performance of OIS in many digital cameras by
taking full advantage of the smaller components and therefore reduced mass to move
during stabilisation.
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.
Many OIS systems may only be able to handle m

ovement frequencies up to a certain
level. Based on our lab tests, Nokia’s new OIS system can cater for around 50% more
movements per second than conventional OIS systems – up to around 500
movements every second! Besides the high frequency compensation, the system also
needs to be able to respond extremely quickly to unintended movement to avoid so
called “phase shift” or compensation lag. To help achieve this very fast reaction time,
Nokia uses a closed loop system where the position of the lens assembly is monitored in
real time, even whilst it’s moving to its calculated position allowing it to be continuously updated regardless of how random the camera movement is. This process of checking
operates at a rate of up to 5x more frequently than typical OIS systems, approximately
300 times faster than that of the average human reaction time to an expected event.
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. As a point of reference, and dependin

g on
the user’s ability to hold the device still, shutter speeds slower than 1/30
typically results in camera shake. Depending on the amount of camera movement
requiring compensation we’ve found in testing that shutter speeds as long as 1/4
second can be used. This is a 3EV improvement or 8x longer shutter speed — which we
believe to be a new benchmark! This extends the low light performance of the camera to
a whole new level.


Category: Lumia, Nokia, Windows Phone

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