Sunday, January 13, 2013
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| Nokia PureView Technolgy |
The theory behind this technology is that a pixel oversampling technique that reduces an image taken at full resolution into a lower resolution picture, thus achieving higher definition and light sensitivity, and enables lossless zoom. It is the combination of a 1/1.2" large,[7] very high resolution 41Mpix image sensor with high performance Carl Zeiss optics. The large sensor enables pixel oversampling, which means the combination of many sensor pixels into one image pixel. PureView imaging technology delivers high image quality, lossless zoom, and improved low light performance (see below). It dispenses with the usual scaling/interpolation model of digital zoom used in virtually all Smartphone, 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. In both video and stills, this technique provides greater zoom levels as the output picture size reduces, enabling 4x zoom in full HD 1080p video, 6x lossless zoom for 720p HD, and 12x zoom for nHD (640x360) video.
You can experience the difference on a normal camera and with a camera using PureView technology. See the below given video.
Do you know how this technology works:
PureView Technology has two main features: 1. image
quality and 2. lossless zoom.
In terms of image quality, you can take either
eight-, five-, or three-megapixel images employing the PureView Technology. For
the rest of the article we will only use eight-megapixel examples but the
principle applies the same way to five- or two-megapixel photos.
Nokia is using something called “pixel oversampling”
which could be misleading, because oversampling in this case doesn’t refer to
inflating pixels but creating a so-called “super-pixel”. In case of
eight-megapixel images, there’s a ratio of 5 to 1 in creating images (from full
size to eight). This picture oversampling combines multiple pixels into a
single pixel. The amount of pixels combined depends on the resolution of your
final image: eight megapixel images contain super-pixels combined of less
pixels than three-megapixel pictures.
To use Nokia’s own description, “you keep virtually
all the detail, but filter away visual noise from the image. The speckled,
grainy look you tend to get in low-lighting conditions is greatly reduced”.
As far as lossless zoom is concerned, the 808
PureView is not employing any optical zooming and no digital zooming either
(which means no pixelation). But how does it zoom then? Whenever you zoom into
a portion of the screen, the amount of pixels required to create super-pixels
is reduced (to zero when reaching maximum zoom).
To put this in a simple context, when you reach the
maximum zoom available according to the final image size (eight-, five-,
three-megapixels only, zooming is disabled in full-resolution mode) you will
basically get a 1:1 crop of the image sensor. At maximum zoom, you will see
exactly the image captured by the sensor, with no modifications. Nokia adds:
“because only the center of the optics are used where there is less
diffraction, you get better optical performance — including low distortion, no
vignetting, and high levels of resolved detail”.
This exact procedure is applied when recording
videos. 1080p videos will benefit from 4x lossless zoom by cropping towards
1:1, and 720p videos can zoom to 6x, all in a lossless way.
