A novel disparity-assisted block matching-based approach for super-resolution of light field images

Currently, available plenoptic imaging technology has limited resolution. That makes it challenging to use this technology in applications, where sharpness is essential, such as film industry. Previous attempts aimed at enhancing the spatial resolution of plenoptic light field (LF) images were based on block and patch matching inherited from classical image super-resolution, where multiple views were considered as separate frames. By contrast to these approaches, a novel super-resolution technique is proposed in this paper with a focus on exploiting estimated disparity information to reduce the matching area in the super-resolution process. We estimate the disparity information from the interpolated LR view point images (VPs). We denote our method as light field block matching super-resolution. We additionally combine our novel super-resolution method with directionally adaptive image interpolation from [1] to preserve sharpness of the high-resolution images. We prove a steady gain in the PSNR and SSIM quality of the super-resolved images for the resolution enhancement factor 8x8 as compared to the recent approaches and also to our previous work [2]

The suitability of lightfield camera depth maps for coordinate measurement applications

Plenoptic cameras can capture 3D information in one exposure without the need for structured illumination, allowing grey scale depth maps of the captured image to be created. The Lytro, a consumer grade plenoptic camera, provides a cost effective method of measuring depth of multiple objects under controlled lightning conditions. In this research, camera control variables, environmental sensitivity, image distortion characteristics, and the effective working range of two Lytro first generation cameras were evaluated. In addition, a calibration process has been created, for the Lytro cameras, to deliver three dimensional output depth maps represented in SI units (metre). The novel results show depth accuracy and repeatability of +10.0 mm to -20.0 mm, and 0.5 mm respectively. For the lateral X and Y coordinates, the accuracy was +1.56 m to −2.59 m and the repeatability was 0.25 µm

Absolute depth using low-cost light field cameras

Digital cameras are increasingly used for measurement tasks within engineering scenarios, often being part of metrology platforms. Existing cameras are well equipped to provide 2D information about the fields of view (FOV) they observe, the objects within the FOV, and the accompanying environments. But for some applications these 2D results are not sufficient, specifically applications that require Z dimensional data (depth data) along with the X and Y dimensional data. New designs of camera systems have previously been developed by integrating multiple cameras to provide 3D data, ranging from 2 camera photogrammetry to multiple camera stereo systems. Many earlier attempts to record 3D data on 2D sensors have been completed, and likewise many research groups around the world are currently working on camera technology but from different perspectives; computer vision, algorithm development, metrology, etc. Plenoptic or Lightfield camera technology was defined as a technique over 100 years ago but has remained dormant as a potential metrology instrument. Lightfield cameras utilize an additional Micro Lens Array (MLA) in front of the imaging sensor, to create multiple viewpoints of the same scene and allow encoding of depth information. A small number of companies have explored the potential of lightfield cameras, but in the majority, these have been aimed at domestic consumer photography, only ever recording scenes as relative scale greyscale images. This research considers the potential for lightfield cameras to be used for world scene metrology applications, specifically to record absolute coordinate data. Specific interest has been paid to a range of low cost lightfield cameras to; understand the functional/behavioural characteristics of the optics, identify potential need for optical and/or algorithm development, define sensitivity, repeatability and accuracy characteristics and limiting thresholds of use, and allow quantified 3D absolute scale coordinate data to be extracted from the images. The novel output of this work is; an analysis of lightfield camera system sensitivity leading to the definition of Active Zones (linear data generation good data) and In-active Zones (non-linear data generation poor data), development of bespoke calibration algorithms that remove radial/tangential distortion from the data captured using any MLA based camera, and, a light field camera independent algorithm that allows the delivery of 3D coordinate data in absolute units within a well-defined measurable range from a given camera

Fusion of computed point clouds and integral-imaging concepts for full-parallax 3D display

During the last century, various technologies of 3D image capturing and visualization have spotlighted, due to both their pioneering nature and the aspiration to extend the applications of conventional 2D imaging technology to 3D scenes. Besides, thanks to advances in opto-electronic imaging technologies, the possibilities of capturing and transmitting 2D images in real-time have progressed significantly, and boosted the growth of 3D image capturing, processing, transmission and as well as display techniques. Among the latter, integral-imaging technology has been considered as one of the promising ones to restore real 3D scenes through the use of a multi-view visualization system that provides to observers with a sense of immersive depth. Many research groups and companies have researched this novel technique with different approaches, and occasions for various complements. In this work, we followed this trend, but processed through our novel strategies and algorithms. Thus, we may say that our approach is innovative, when compared to conventional proposals. The main objective of our research is to develop techniques that allow recording and simulating the natural scene in 3D by using several cameras which have different types and characteristics. Then, we compose a dense 3D scene from the computed 3D data by using various methods and techniques. Finally, we provide a volumetric scene which is restored with great similarity to the original shape, through a comprehensive 3D monitor and/or display system. Our Proposed integral-imaging monitor shows an immersive experience to multiple observers. In this thesis we address the challenges of integral image production techniques based on the computerized 3D information, and we focus in particular on the implementation of full-parallax 3D display system. We have also made progress in overcoming the limitations of the conventional integral-imaging technique. In addition, we have developed different refinement methodologies and restoration strategies for the composed depth information. Finally, we have applied an adequate solution that reduces the computation times significantly, associated with the repetitive calculation phase in the generation of an integral image. All these results are presented by the corresponding images and proposed display experiments