Calibration is an important part of light field photography: Image processing and image quality can be significantly improved when the physical properties of the camera are known. More specifically, geometric information about the microlenses in a microlens-array-based light field camera can help create more precise depth maps with fewer errors.
Yunsu Bok and colleagues from the Korean Advanced Institute of Science and Technology (KAIST) have devised a new method for geometric calibration which – in contrast to conventional methods – does not rely on processing sub-aperture images. Instead, they extract line features and compute a light field camera’s geometric parameters directly from RAW images. Continue reading
Ricoh researchers Sapna A. Shroff and Kathrin Berkner have lodged a patent application that describes a new way to dynamically adjust the recording parameters of a light field camera. The US Patent and Trademark Office has recently published patent application US20140192255, entitled “Dynamic Adjustment of Multimode Lightfield Imaging System Using Exposure Condition and Filter Position”, in which the authors use a non-homogeneous filter module at the pupil plane of a multimode imaging system, which can be moved and thus used to modify the imaging system’s exposure conditions. Continue reading
Just a few years ago, mobile displays took a leap forward with increased pixel densities that ensure crisp images on realtively small screens. Today, most smartphones feature displays with up to 538 pixels per inch (ppi) – a resolution that is much higher than what the human eye can see. So what’s the next display innovation we can look forward to?
In her recent article on IEEE Spectrum, Sarah Lewin introduced two companies that are working on making what she calls “holographic” light field displays (i.e. glasses-free 3D displays) a reality.
Ostendo Technologies recently presented the results of nine years’ work at the Display Week conference: An array of 4×2 Quantum Photonic Imager chips (each consisting of LEDs, image processors and embedded rendering software) plus microlens array form a 1 megapixel (1024x768px, XGA resolution) prototype display which sends out light not into every direction – like conventional displays do – but rather into very narrow, collimated angles of light. This enables the prototype to emit different images into different directions, producing about 2,500 different perspective views, so the image and motion displayed appear consistent regardless of the viewer’s position. Continue reading
In order to record colour images, camera sensors typically use a colour filter array consisting of red, green, and blue filters on top of the light-intensity sensing sub-pixels. After recording each sub-pixel’s light intensity, the so-called “demosaic” process combines four monochrome sub-pixels (2x red, 2x green, 1x blue) into a single pixel containing RGB colour information.
In microlens-based light field cameras, this “demosaic” job may result in a blur effect around the boundaries of objects in the final image.
Image Sensors World found a patent application by Samsung which can solve this blur-problem: In the patent application entitled “Photographing device and photographing method for taking picture by using a plurality of microlenses”, authors Tae-Hee Lee et al. propose moving the colour filter in front of the microlenses (instead of having them behind the microlenses), creating single-colour sub-images. Continue reading
Light field technology is making its way into the mainstream, but the production and assembly of some of its components has not quite reached an efficient scale of mass production.
A typical light field sensor consists of an ordinary image sensor and a microlens array (MLA) or printed mask.
In the assembly of light field sensors, one of the most vital processes is the precise adjustment of the MLA‘s position on the sensor. This adjustment is required for every individual sensor and can thus take up a long time. Since the MLA is usually positioned using screws or springs, physical impact on the light field camera may displace the light field sensor’s layers.
With patent application US 20140183334 A1 “Image sensor for light field device and manufacturing method thereof“, recently discovered by Image Sensors World, Visera Technologies is aiming for an integrated manufacturing method for light field sensors: Authors Wei-Ko Wang and colleagues propose a system where two layers of microlenses (and an intermediate space layer) are formed directly on the image sensor using semiconductor processes. Continue reading