Pushing the boundaries of digital imaging
PUSHING THE BOUNDARIES OF DIGITAL IMAGING This whitepaper introduces Nokia Lumia 1020 and its new hardware and software camera innovations. The Nokia Lumia 1020 re-invents zoom by combining a very large sensor with OIS for the first time. Also it pushes the boundaries of smartphone creative photography with a new intuitive touch UI that provides manual controls for shutter speed and other controls.
CONTENTS Background...........................................................................................................................................................................4 Best of both worlds: Sharpness and low light.....................................................................................................................4 Sharpness is more than just megapixels................................................................................................................
BACKGROUND The Nokia 808 PureView camera phone, launched in 2012, included world-leading advances in image quality in terms of resolution, sharpness and clarity. Innovative oversampling technology provided a level of image detail previously unseen in mobile, or even small scale, digital imaging systems. In addition, pixel oversampling combined many pixels to create a single super-pixel. This allowed us to keep virtually all the detail but to filter visual noise away from the image.
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. Sharpness is more than just megapixels Resolution is the sum of several parts in the imaging chain, starting from how we capture images, how much hand-shake is involved, and ending with technical functions including the camera optics, the image sensor, and the algorithms.
Oversampling results in 5MP photos with amazing detail In traditional imaging systems, the true resolution of the system is lower than that of the nominal sensor resolution. The traditional camera sensor resolution may be 5MP, but it does not really capture photos that have five million pixels of independent data. The data is spread across multiple pixels causing, for example, blurring and artifacts.
High resolution zoom In addition to oversampling, the large sensor also allows for high resolution zoom. As you zoom there is no drop in the default 5MP resolution; in other words the high resolution zoom is lossless. The level of pixel oversampling is highest when you’re not using the zoom. It gradually decreases until you hit maximum zoom where the pixels start behaving in a more conventional way. The relationship between zoom level and oversampling is shown in Figure 5.
The advantages of the Nokia Lumia 1020 zoom compared to an optical zoom are: • The aperture size of a typical optical zoom drops dramatically when zoomed in. For example, a typical optical zoom can have aperture size f2.8 in wide, but it can drop to f6 in tele. This means that the camera needs almost a five times longer exposure time in the tele position.
moved with very small motors to counteract the unwanted camera movements detected by a gyroscope. Photos in the dark If you lightly wobble the phone and listen to the camera, you can actually hear the module that absorbs the shaking of your hand. Once the camera is activated, give the phone the same wobble and the magnets kick in and soak up the movements. The standard factor used for determining good low light performance is the amount of visible noise in the image captured.
Image sharpness measured with handshake as function of illuminance With the Lumia 1020 we use a no-compromise xenon flash with very high light output and extremely short flash pulse duration. High flash output provides excellent illumination to targets three metres away, and the short pulse of the xenon flash ensures that the final captured image is extremely sharp while preserving the ambient lighting of the background.
Nokia pro camera “You don’t take a photograph, you make it.” - Ansel Adams To make the most out of the innovative hardware in the Nokia Lumia 1020 we have designed a new camera application called Nokia Pro Camera. It helps you to create the photo you want, and to become a better photographer. It is filled with features previously only found in digital SLR cameras. Taking excellent photos has never been so easy, as complex settings are turned into easy adjustments with immediately visible results.
Zoom reinvented and reframing For stills, the 3X high-resolution zoom has very high image quality, but what is even more interesting is what happens after the photo is taken. By saving a full-resolution photo we can in fact zoom OUT or “un-zoom” from the 5MP image presented for easy sharing after capture, offering a unique way of zooming that has never been possible before.
Lumia 1020 41MP sensor No Zoom 3x Hi-Res Zoom During Capture 5MP oversampled image. Every pixel is using data from many pixels on the sensor 5MP Crop from sensor Traditional 8MP sensor 1280x720 5MP Reframing Post Capture Sensor 640x352 Oversampling 0 2 4 6 8 10 Magnification factor ...up to 25x Camera Roll Image 8MP (3456x2304) Crop & rotate from full resolution image 1280x720 640x352 Figure 12. The high resolution zoom is not locked but can be zoomed out in the post-capture phase.
Photography tools and creative control To help you compose the shot, Nokia Pro Camera has a number of framing grids which can help place the subject in your photo. See figure 15. On top of the viewfinder, you find a dashboard with indicators for all manual controls and their current settings. The default value of each control is auto but tapping the value brings up a control ring where you can adjust the value manually.
if you are in a situation where you don’t want to disturb anyone with the light from your phone. Manual controls: EV, Shutter speed, ISO, Focus, WB Nokia Pro Camera lets you take full control over your camera with a set of manual controls normally only found on advanced SLR cameras. Naturally the default for all controls is ‘auto’ but the UI is very intuitive and it helps you and encourages you to start experimenting with the controls so that you can become a better photographer.
If you’re in a low-light situation and decide to increase the ISO manually, keep Shutter speed set to auto. In this mode, the indicators on the dashboard will show you what shutter speed the camera is going to use. This is because ISO, Shutter speed and EV are interdependent as described in the diagram in figure 18.
Figure 19. Conventional audio recording (on the left) vs. distortion-free Nokia Rich Recording (on the right). Illustration only. Nokia Rich Recording Sound quality is essential for high-quality video recording. In Nokia 808 PureView, we introduced Nokia Rich Recording, a technology developed exclusively to deliver the highest quality stereo audio recording. With Nokia Pro Camera Video we bring Nokia Rich Recording to Lumia 1020.
Photo examples The Nokia Lumia 1020 is designed to deliver the best possible results in real life situations. Be it a rocking sailing boat or a night club filled with motion. Unlike competing devices the Lumia 1020 delivers maximum resolution in all these situations. Figure 20. Manual setting of the long exposure time emphasizes the busy atmosphere at Grand Central station. This image was taken with the Nokia Camera Grip and a tripod (1/3 s exposure time, ISO 100, and EV -0.7) Figure 22.
Figure 24. A woman drinking tea Figure 25. …and her teabag tag.
Figure 26. Take control of shutter speed and create some breathtaking night scenes with light trails by exposing for up to 4s. Figure 27. Crank the ISO up to 3200 to shoot brighter photos with higher shutter speeds. Figure 28. Use exposure value creatively to play with light and to decide which areas are over- or under-exposed. Figure 29. Manual focus makes it easy for you to experiment with distance. You can choose to have a nice Bokeh effect in the foreground or background.
Key technologies and specs • Latest generation 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. See Figure 30. • 35mm equivalent focal length: 25mm for 16:9, 27mm for 4:3 • F-number: f/2.
CREDITS Written by Juha Alakarhu, Kristina Björknäs, Marcus Olsson, Ari Partinen, Eero Salmelin, and Heikki Sassi on behalf of many dedicated Nokia imaging and audio experts. Lumia 1020 photos taken by Ted Bergeron, Kristina Björknäs, Stephen Elop, and Ari Partinen. Figure 31. Mechanical shutter. Illustration only 1 J. Alakarhu, S. Koskinen, E. Tuulos, “Image quality of oversampling cameras,” in Proc.