High dynamic range

About: High dynamic range is a research topic. Over the lifetime, 4280 publications have been published within this topic receiving 76293 citations. The topic is also known as: HDR.

A hands-on approach to high-dynamic-range and superresolution fusion

Abstract: This paper discusses a new framework to enhance image and video quality. Recent advances in high-dynamic-range image fusion and superresolution make it possible to extend the intensity range or to increase the resolution of the image beyond the limitations of the sensor. In this paper, we propose a new way to combine both of these fusion methods in a two-stage scheme. To achieve robust image enhancement in practical application scenarios, we adapt state-of-the-art methods for automatic photometric camera calibration, controlled image acquisition, image fusion and tonemapping. With respect to high-dynamic-range reconstruction, we show that only two input images can sufficiently capture the dynamic range of the scene. The usefulness and performance of this system is demonstrated on images taken with various types of cameras.

High-dynamic range image generation from single low-dynamic range image

Abstract: Due to the growing popularity of high-dynamic range (HDR) image and the high complexity to capture HDR image, researchers focus on converting low-dynamic range (LDR) content to HDR, which gives rise to a number of dynamic range expansion methods. Most of the existing methods try their best to tackle highlight areas during the expanding, however, in some cases, they cannot achieve approving results. In this study, a novel LDR image expansion technique is presented. The technique first detects the highlight areas in image; then preprocesses them and reconstructs the information of these regions; finally, expands the LDR image to HDR. Unlike the existing schemes, the proposed approach escapes the complicated treatment to highlight areas in the process of expansion, which makes the expansion straightforward; at the same time, it facilitates the expansion scheme and minimises the formation of the artefacts. The experimental results show that the proposed method performs well; the tone mapped versions of the produced HDR images are popular. The results of the image quality metric also illustrate that the novel approach can recover more image details with minimised contrast loss and reversal, compared with the existing schemes considered in the comparison.

Broadband Magnetotelluric Instruments for Near-surface and Lithospheric Studies of Electrical Conductivity: A Fennoscandian Pool of Magnetotelluric Instruments

Abstract: A set of three new tensor audiomagnetotelluric – magnetotelluric (AMT-MT) instruments have been assembled in Oulu. Their design is based on the MTU2000 magnetotelluric equipment that was developed earlier in the Uppsala University. The new instruments are broadband systems covering the period range from 0.001 s to d.c. Induction coil magnetometers are used to measure magnetic field in the period range of 0.001–1000 s and fluxgate magnetometers for periods longer than 10 s. The electric field is measured with two 50–200 m long orthogonal electric dipoles using non-polarisable Pb/PbCl2 electrodes. The MT systems are equipped with high dynamic range (24 bit ADC) data recorders having a maximum sampling frequency of 3000 Hz and possibility for dual band burst recording. Monitoring of the system health with SMS messages helps to maintain long period observations allowing continuous measurements and reducing the maintenance efforts and costs. The three new instruments extend the Fennoscandian pool of homogeneous MT equipments into 14 systems and allow synchronous array measurements. This makes it possible to use multisite data processing techniques and therefore considerably improve the data quality, especially in electromagnetically noisy regions. The instrument pool can be used in a broad range of applications to study the crust and upper mantle.

Recursive HDR image generation from differently exposed images based on local image properties

Abstract: Dynamic range limitation of CCD-cameras may cause distortions and data loses in images. Such limitations are strongly effect to the further image processing. This paper describes method of combining information from differently exposed images for increasing dynamic range. Initially image is decomposed into set of regions. For each of region we compute detail evaluation function which represents its local properties. Namely mean intensity, intensity deviation and entropy. This function is used to detect regions with high dynamic range. The regions with high dynamic range are then recursively decomposed. This process iterates until all HDR regions are processed, or the size of these regions is too small for decomposition. During the process of decomposition we select the best exposure for each sub-region. For smoothing interregional transaction we used Gaussian-based smoothing function. Proposed technique allows recovering details in overexposed and underexposed parts of image. Our experiments show effectiveness of algorithm for the scenes with high dynamic range. Proposed method shows robust results even if the exposure difference between input images is 2-stops or higher.

3.2: High Dynamic Range Projection Systems

Abstract: Digital cinema and home theatre applications need to compete with analog film in terms of image quality. The single most important performance specification of a projection system, and the largest gap in the competition between digital and analog projectors, is the relatively low dynamic range of luminance of current digital projectors. In this paper we introduce a novel digital system capable of displaying images with a high enough dynamic range to rival analog film. The projection system described is based on a serial combination of light modulating devices, such as two liquid crystal micro-display panels within a projection light engine. One of the modulation steps can be of lower spatial resolution and contrast. This increases the optical efficiency of the system and avoids optical artifacts. We describe several hardware implementations of this approach as well as the required image processing. Finally, we present an evaluation of the designs in terms of performance, image quality and cost.