Sunday, July 10, 2011

Nokia N9 Flagship Camera Phone Goes Down in Pixel Size and Count

Nokia Conversations, an official Nokia blog, published an article on camera optimization in the new N9, the company's new flagship camera phone. The camera resolution is 8MP - a step back from 12MP ised in last year's flagship N8. The camera feature list includes:
  • Industry-first imaging sensor which is FULLY optimised for BOTH 16:9 AND 4:3 images
  • Super wide-angle optics – the widest in the industry. Up to as much as 60% more viewing area than other broadly comparable devices
  • f/2.2 aperture – largest ever in a mobile device
  • Extremely responsive, especially switching from stills to video and vice-versa and shot to shot
  • Full time continuous AF in BOTH video and stills plus face detection
  • AMBR – Automatic Motion Blur Reduction
The increased sensor area optimization in 4:3 and 16:9 modes as explained on the picture below means a sensor has more pixels than one needs at any one time. While N9 spec says 8MP, the sensor is actually 8.7MP:


The new sensor is said to be designed and developed to Nokia own specification and exclusively supplied to Nokia. The sensor is said to use smaller pixels than 1.75um found in last year's N8. The article explains the sensor design considerations:

"it was obvious the camera was going to have to be significantly slimmer [than one in N8]. 12-megapixels in a module that size wasn't going to be possible unless we'd been prepared to compromise the low light performance. We had a lot of internal debate around that point! On one side there are still a lot of people who believe megapixels is a measure of camera performance, while a growing number of others know it can result in compromise. We had the same challenge with the Nokia N8, should we go for 12-megapixels like others with smaller pixels and a smaller module or do what we felt was right? It's always been our intent to provide cameras with a focus on real world performance. But on the flip side we need to consider what's believed to be competitive in the market. We don't believe in adding pixels just for the sake of it, if it doesn't provide any genuine benefit...

Two developments helped us greatly here.

1. Super large f/2.2 aperture allowing approximately 75% more light to reach the image sensor. This is the largest aperture ever incorporated in to a mobile and larger than most digital cameras.

2. Adoption of the latest generation sensors which provide increased sensitivity as well as improvements in the processing of data resulting in lower visual noise.

Combining these improvements, the low light performance between the new Nokia N9 and the N8 is broadly comparable depending on your preference of noise handling.
"

2 comments:

  1. This is a good example of the empty megapixels. The blur circle is nominally 2.2 µm for a diffraction limited optic and the pixel is 1.75. Although oversampling can present a better image, the CAMERA does not have 8 megapixels of resolution the SENSOR does. The CAMERA resolution is about 6.4 megapixel.

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  2. To use f/2.2 aperture for low-light condition, do they reduce depth of field instead? Or any Extended depth of field technique included?

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