This is an old revision of this page, as edited by RHaworth (talk | contribs) at 19:13, 29 February 2012 (Deleted revision of PureView Pro (as of 2012-02-28, at 09:14:51) by Cchallag - a bit of spam removed). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 19:13, 29 February 2012 by RHaworth (talk | contribs) (Deleted revision of PureView Pro (as of 2012-02-28, at 09:14:51) by Cchallag - a bit of spam removed)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)PureView Pro is an imaging technology used in Nokia 808 Pureview device. It is the combination of a large, super high resolution 41Mpix with high performance Carl Zeiss optics. The large sensor enables pixel oversampling, which means the combination of many pixels into one perfect pixel. PureView imaging technology delivers amazing image quality, lossless zoom, and superior low light performance. It dispenses with the usual scaling/interpolation model of digital zoom used in virtually all smartphones, as well as optical zoom used in most digital cameras, where a series of lens elements moves back and forth to vary the magnification and field of view. Instead, it will give around 3x lossless zoom for stills, and 4x zoom in full HD 1080p, for 720p HD video, 6x lossless zoom and for nHD (640x360) video, 12x zoom.
PureView Pro specifications
- 41Mpix sensor with pixel oversampling
- Lossless zoom: 3x for stills, 4x for full HD 1080p video
- Carl Zeiss optics
- Focal length: 8.02mm
- 35mm equivalent focal length:
- 26mm, 16:9
- 28mm, 4:3
- F-number: f/2.4
- Focus range:
- 15cm – Infinity (throughout the zoom range)
- Construction:
- 5 elements, 1 group. All lens surfaces are spherical
- One high-index, low-dispersion glass mold lens
- Mechanical shutter with neutral density filter
- Optical format: 1/1.2"
- Total number of pixels: 7728 x 5368
- Pixel Size: 1.4 microns
Super high resolution sensor
PureView Pro sensor has an active area of 7728 x 5368 pixels, totaling over 41Mpix. Depending on the aspect ratio user chose, it will use 7728 x 4354 pixels for 16:9 images/videos, or 7152 x 5368 pixels for 4:3 images/videos. What happens next depends on the settings and whether or not zoom is used. But to give an idea, the default still image setting is 5Mpix at 16:9, and for video it’s 1080p at 30fps. Using these settings, the zoom is around 3x for stills and 4x for video. Conventional digital zoom tends to scale up images from a relatively low resolution, resulting in poor image quality.
Zoom
Zoom with the PureView Pro is user just selecting the relevant area of the sensor. So with no zoom, the full area of the sensor corresponding to the aspect ratio is used. The limit of the zoom (regardless of the resolution setting for stills or video) is reached when the selected output resolution becomes the same as the input resolution. That means once the area of the sensor reaches 3072 x 1728, the zoom limit is reached. This means the zoom is always true to the image user wants. The way PureView Pro zoom works gives you many benefits. But the main one is undoubtedly ‘pixel oversampling’. Pixel oversampling combines many pixels to create a single (super) pixel. When this happens, all the details are kept, but filter away visual noise from the image. The speckled, grainy look tend to get in low-lighting conditions is greatly reduced. And in good light, visual noise is virtually non-existent. Which means the images which are taken can take are more natural and beautiful than ever. They are purer, perhaps a more accurate representation of the original subject. The level of pixel oversampling is highest when zoom is not used. It gradually decreases until the maximum zoom is hit, where there is no oversampling. At this stage, PureView Pro optics and pixels start behaving in a more conventional way. But because only the center of the optics are used, where the best optical performance is achieved – including low distortion, no vignetting and highest levels of resolved detail. The system gives the best balance between zoom and oversampling based on how it is framed and composed the scene or subject
Quality not quantity
Everyone inevitably home in on the number of pixels the PureView pro packs, but the point is how they're used. The main way to build smaller cameras over the years has been to reduce the pixel size. These have shrunk just over the past 6 years from 2.2 microns, to 1.75 microns, to 1.4 microns. Some new products are on the way with 1.1 micron pixels. But the smaller the pixel, the less photons each pixel is able to collect means less photons, less image quality. There’s also more visual noise in images/videos, and various other knock on effects.
When new, smaller pixel size sensors are first released, they tend to be worse than the previous generation. While others jump in, banking on pixel numbers instead of performance, PureView Pro skips early iterations. PureView Pro makes choices focused on performance rather than pixels for pixels’ sake. Fewer but better pixels can provide not just better image and video quality, but better overall user benefits and system capability
Pixels fixation
It all stems from the very early days of digital cameras, when image quality was affected by the limited number of pixels available. As the pixel numbers increased, image quality dramatically improved. However, once the resolution reached around 5Mpix-6Mpix, the real-world benefits became debatable. But by then, the market had made a direct correlation between number of pixels and quality of image. The more pixels the better, was the received wisdom. And this thinking has stuck. Though today manufacturers would happily reduce the number of pixels in their cameras, and instead concentrate on their lenses and sensors, they’re not so sure the market would accept this. Why more than 5Mpix is needed. The most popular argument heard was the versatility the extra pixels provide for the ability to crop the images or to create the large prints.
Cropping
PureView Pro, enables to frame your shots on the spot. However, framing can be differed until later, as there are user settings in the Creative Shooting Mode for capturing ‘full-resolution’ images. User can choose to zoom into any part of the image, and find new creative views in the original. Actually, user can shoot quickly and crop later with other larger display. User can re-frame many times, scale the image to preferred output resolution, and choose the relevant downscaling method depending on the usage.
Processing power
One of the reasons the PureView Pro has been challenging the most powerful mobile chipsets as they have an upper limit of around 20Mpix image processing capability. PureView Pro eats up more than double that. For video, the amount of pixels handled through the processing chain is staggering — over 1 billion pixels per second and 16x oversampling. That’s a throughput of pixels 16 times greater than many other smartphones. Most smartphone manufacturers crop off a section of the sensor to ease the processing load. By contrast, the PureView Pro has no limited field of view. Plus, it provides lossless zooming capability, which is output resolution dependent. Full HD 1080p gives 4x zoom. For 720p HD video, 6x lossless zoom. And for nHD (640x360) video, 12x zoom. In addition, encoding is up to 25mbps in high profile H.264 format. To make this all happen, PureView Pro sensor is developed with a special companion processor that handles pixel scaling before sending the required number to the main image processor.
Improved video auto focus
PureView Pro comes with dramatically improved video auto focus due larger image sensor (5x larger than other smartphones) as the optics gives a relatively shallow depth of field. Moreover pixel oversampling is also used in video to achieve low visual noise with extremely high levels of detail. As a result, auto focus system is made more precise, sensitive and controllable. PureView Pro gives continuous auto focus in all shooting modes and close-up focus is also improved.