Friday, July 12, 2013

Nokia Lumia 1020 Features 1.1um BSI Pixel 41MP Sensor

Nokia Conversations: Nokia announces Lumia 1020 Windows 8 smartphone featuring a next generation 41MP sensor combined with 6-element OIS lens. The new sensor has 1.1um BSI pixels, while the last year's 41MP PureView model 808 had 1.4um FSI pixels. The smaller pixel allows shrink the sensor size from 1/1.2-inch to 1/1.5-inch.

Nokia Lumia 1020
Nokia offers a camera grip for Lumia 1020 with an integrated
shutter button and a battery

Few quotes from Lumia 1020 whitepaper:

"The second generation 41 megapixel sensor uses the latest generation 1.1 micron back-side-illuminated (BSI) pixels, providing excellent noise performance as well as benchmark resolution. The sensor format is 1/1.5” and it is up to five times larger than typical smartphone sensors. The redesigned sensor provides all the imaging innovations introduced with Nokia 808 PureView – meaning high resolution zooming and pixel oversampling – plus new innovations in a revised, more modern camera module."

"One of the critical design decisions in a camera is balancing the subjective image sharpness and noise performance. Image sharpness and low light performance (noise or grain) are two sides of the same coin in camera systems and it is extremely difficult to achieve benchmark performance in both simultaneously. However this is exactly what we have done with the Nokia Lumia 1020."

"Together with our partner Carl Zeiss, we yet again pushed the limits of optical design to match the resolution of the 41 megapixel camera sensor. To provide the best optical resolution we increased the number of lenses used from the five in the award-winning Nokia 808 PureView, to six. The first lens element is made of high precision glass, and five of the lenses are moulded high-performance plastic, taking lens manufacturing precision to the next level."

Image oversampling advantages
Oversampling vs. high resolution zoom in the case of Lumia 1020
(blue) compared with conventional digital zoom (orange).
High oversampling is said to mean high image quality

"Image sharpness is usually measured using a tripod (an accessory that the average person rarely carries) in good lighting conditions (also a luxury). We replicated real life situations, using a hand-shake simulator running at 4Hz frequency, with the Nokia Lumia 1020 challenging a market leading 13MP device in multiple lighting conditions. The Lumia 1020 was tested using the more ‘shareable’ 5MP images and the measurements were done from centre frame for both devices.

The results are depicted in Figure 8. The graph shows that Nokia Lumia 1020 resolves very close to the theoretical maximum of the 5MP image in good lighting conditions, but what is even more remarkable is that because of the combination of OIS and xenon flash we can provide practically the same huge resolution also in extremely dark conditions. And this was measured while introducing handshake to the device! Even without help from the xenon flash the resolution never drops below 50 percent of the theoretical maximum.

In low light conditions the competitor device was only able to provide around 10 percent of its theoretical maximum resolution, and even in really bright lighting conditions only 40 percent of its capability was used. So one might ask, why use 13 megapixels, if only 10 percent of the theoretical resolution can be used?

The high resolution zoom is not locked but can be zoomed out in the post-capture
phase. Then magnification can be done all the way to 25X (or 31X for 4:3 images).

Key specs:

  • High-performance BSI sensor
  • Sensor size 1/1.5”, 41MP, pixel size 1.1 micron, true 16:9/4:3 aspect ratio. Total sensor is 7712x5360=41.3MP. 16:9 mode is 7712x4352=33.6MP and 4:3 mode is
  • 7136x5360=38.2MP
  • 35mm equivalent focal length: 25mm for 16:9, 27mm for 4:3
  • F-number: f/2.2
  • Mechanical shutter
  • Optical image stabilisation (new type of barrel shift actuator which enables moving a heavy and complex full lens assembly)
  • System of 6 lenses (5 plastic molded high performance plastic, one high precision glass element)
  • Nokia image processing and pixel oversampling technology
  • Nokia-developed 3A algorithms (auto-exposure, auto-focus, auto-white-balance)
  • New white balance technology
  • New generation powerful xenon flash with flat capacitor technology which enables more power in a more compact package
  • Video LED light

Update: Nokia Conversations published a post on what large resolution gives.


  1. Nokia did good job by balancing module size, sharpness and low light noise. Oversampling probably will offer better image quality than optical zoom in a smaller form factor. However, i am wondering about the max frame rate and shot to shot latency, not sure whether Nokia addresses the issue as well as iphone does. We will see...

  2. Who makes the sensor for them? Both the FSI and the BSI?

    1. Chipworks found Toshiba inside 808 model:

  3. the last presentation picture is likes muti-aspect sensor of GH lumix

  4. Does the sensor (CCD)size = 1 inch by 1.5 inches?

    1. No, sensor sizes are very confusing. The original 1 inch image tube had a 5/8 inch diagonal scanned area and a 4:3 aspect ratio so the scanned area was 3/8 x 1/2 inch. The "1 inch" designator came from the outside diameter of the glass tube envelope. This led to labeling the image sensor active areas based on the size of the 1-inch scanned area. For simplicity (sort of), 5/8 inch was converted to 16 mm. Then, 2/3 inch became 11mm (6.6 x 8.8 mm active area).

      1/1.5 inch is the same as 2/3 inch but probably stated as 1/1.5 so it can be directly compared to 1/2, 1/3, etc. This should make the diameter of the circle in the illustration 11 mm but it calculates to about 9.8 mm which would make the size more like 1/1.63. On the other hand, many sensor manufacturers make 1/3 inch sensors, for instance, that are a lot of different sizes near the 5.5 mm diagonal that would be properly scaled.


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