Showing papers on "High-dynamic-range imaging published in 2006"

Programmable imaging : Towards a flexible camera

Abstract: In this paper, we introduce the notion of a programmable imaging system. Such an imaging system provides a human user or a vision system significant control over the radiometric and geometric characteristics of the system. This flexibility is achieved using a programmable array of micro-mirrors. The orientations of the mirrors of the array can be controlled with high precision over space and time. This enables the system to select and modulate rays from the scene's light field based on the needs of the application at hand. We have implemented a programmable imaging system that uses a digital micro-mirror device (DMD), which is used in digital light processing. Although the mirrors of this device can only be positioned in one of two states, we show that our system can be used to implement a wide variety of imaging functions, including, high dynamic range imaging, feature detection, and object recognition. We also describe how a micro-mirror array that allows full control over the orientations of its mirrors can be used to instantly change the field of view and resolution characteristics of the imaging system. We conclude with a discussion on the implications of programmable imaging for computer vision.

Color appearance in high-dynamic-range imaging

Abstract: When viewing images on a monitor, we are adapted to the lighting conditions of our viewing environment as well as the monitor itself, which can be very different from the lighting conditions in which the images were taken. As a result, our perception of these photographs depends directly on the environment in which they are displayed. For high-dynamic-range images, the disconnect in the perception of scene and viewing environments is potentially much larger than in conventional film and photography. To prepare an im- age for display, luminance compression alone is therefore not suffi- cient. We propose to augment current tone reproduction operators with the application of color appearance models as an independent preprocessing step to preserve chromatic appearance across scene and display environments. The method is independent of any spe- cific tone reproduction operator and color appearance model (CAM) so that for each application the most suitable tone reproduction op- erator and CAM can be selected. © 2006 SPIE and

Programmable Imaging: Towards a Flexible Camera

Abstract: In this paper, we introduce the notion of a programmable imaging system. Such an imaging system provides a human user or a vision system significant control over the radiometric and geometric characteristics of the system. This flexibility is achieved using a programmable array of micro-mirrors. The orientations of the mirrors of the array can be controlled with high precision over space and time. This enables the system to select and modulate rays from the scene's light field based on the needs of the application at hand. We have implemented a programmable imaging system that uses a digital micro-mirror device (DMD), which is used in digital light processing. Although the mirrors of this device can only be positioned in one of two states, we show that our system can be used to implement a wide variety of imaging functions, including, high dynamic range imaging, feature detection, and object recognition. We also describe how a micro-mirror array that allows full control over the orientations of its mirrors can be used to instantly change the field of view and resolution characteristics of the imaging system. We conclude with a discussion on the implications of programmable imaging for computer vision.

Lossy compression of high dynamic range images and video

Abstract: Most common image and video formats have been designed to work with existing output devices, like LCD or CRT monitors. As the display technology makes huge progress, these formats can no longer represent the data that the new devices can display. Therefore a shift towards higher precision image and video formats seems to be imminent. To overcome limitations of the common image and video formats, such as JPEG, PNG or MPEG, we propose a novel color space, which can accommodate an extended dynamic range and guarantees the precision that is below the visibility threshold. The proposed color space, which is derived from the contrast detection data, can represent the full range of luminance values and the complete color gamut that is visible to the human eye. We show that only minor changes are required to the existing encoding algorithms to accommodate a new color space and therefore greatly enhance information content of the visual data. We demonstrate this on two compression algorithms for High Dynamic Range (HDR) visual data: for static images and for video. We argue that the proposed HDR representation is a simple and universal way to encode visual data independently of the display or capture technology.

High dynamic range imaging by pupil single‐mode filtering and remapping

Abstract: Because of atmospheric turbulence, obtaining high angular resolution images with a high dynamic range is difficult even in the near-infrared domain of wavelengths. We propose a novel technique to overcome this issue. The fundamental idea is to apply techniques developed for long baseline interferometry to the case of a single-aperture telescope. The pupil of the telescope is broken down into coherent subapertures each feeding a single-mode fibre. A remapping of the exit pupil allows interfering all subapertures non-redundantly. A diffraction-limited image with very high dynamic range is reconstructed from the fringe pattern analysis with aperture synthesis techniques, free of speckle noise. The performances of the technique are demonstrated with simulations in the visible range with an 8-m telescope. Raw dynamic ranges of 1:10 6 can be obtained in only a few tens of seconds of integration time for bright objects.

A Novel Lighting Control System Integrating High Dynamic Range Imaging and DALI

Abstract: Conventional photosensor-based lighting control systems rely on an integrated photosensor signal that senses the overall illuminance within a space and is calibrated to address performance at a specific critical task point. All surfaces within the field of view (FOV) of the photosensor influence this signal. This paper presents a new method of lighting control that applies an inexpensive image sensor as the light sensing device in conjunction with a computer graphics technique known as High Dynamic Range imaging. A wide range of lighting levels can be evaluated using this technique, and a single sensor is capable of estimating the illuminance levels simultaneously at multiple locations on the work plane. This paper describes a calibration procedure to derive space illuminance information from the images during system operation. It also provides an algorithm to control individual luminaires to achieve different target illuminances at different points on the work plane. The solution takes full advan...

High dynamic range for contrast enhancement

Abstract: Video image quality improving technologies produce remarkable achievements as display devices make rapid progress. However, there exist some limitations on intensity representation of display and acquisition devices to reproduce the real world video images. Various contrast enhancement (CE) algorithms have been developed and applied to overcome those limitations but there are many drawbacks such as color information change, loss of the lighting information, and excessive enhancement. This paper proposes a CE algorithm based on high dynamic range (HDR) imaging. First, an input image is determined whether or not it requires CE in a pre-processing step using the proposed auto exposure algorithm. Then, multiple images are generated by applying the intensity mapping function to an input image. At last, an HDR image is constructed with multiple images, in which registration of multiple images is not required. So, the proposed CE algorithm could increase the dynamic range and thus increase the contrast of an input image. The proposed CE method makes use of different intensity information from multiple images, therefore, the performance of the proposed method is better than that of existing CE algorithms. Experiments with three real images show the effectiveness of the proposed CE algorithm

High dynamic range imaging with a single-mode pupil remapping system : a self-calibration algorithm for redundant interferometric arrays

Abstract: The correction of the influence of phase corrugation in the pupil plane is a fundamental issue in achieving high dynamic range imaging. In this paper, we investigate an instrumental setup which consists in applying interferometric techniques on a single telescope, by filtering and dividing the pupil with an array of single-mode fibers. We developed a new algorithm, which makes use of the fact that we have a redundant interferometric array, to completely disentangle the astronomical object from the atmospheric perturbations (phase and scintillation). This self-calibrating algorithm can also be applied to any - diluted or not - redundant interferometric setup. On an 8 meter telescope observing at a wavelength of 630 nm, our simulations show that a single mode pupil remapping system could achieve, at a few resolution elements from the central star, a raw dynamic range up to 10^6; depending on the brightness of the source. The self calibration algorithm proved to be very efficient, allowing image reconstruction of faint sources (mag = 15) even though the signal-to-noise ratio of individual spatial frequencies are of the order of 0.1. We finally note that the instrument could be more sensitive by combining this setup with an adaptive optics system. The dynamic range would however be limited by the noise of the small, high frequency, displacements of the deformable mirror.

Image acquisition technique for high dynamic range scenes using a multiband camera

Abstract: Multiband cameras have been studied and developed for accurate color reproduction. On the other hand, high dynamic range image acquisition is also strongly desired in many applications. Multiband cameras can potentially meet both needs if their sensitivities are properly controlled. In this article, a method for expansion of the dynamic range that uses a six-band camera consisting of three high-sensitivity bands and three low-sensitivity bands is introduced. Experimental results demonstrating the effectiveness of the method are also shown. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 294–302, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20231

Exposure time estimation for high dynamic range imaging with hand held camera

Abstract: The limited dynamic range of a camera may be extended by composing differently exposed images of the same scene. The nonlinear camera has to be calibrated ra- diometrically first. We show that the calibration process can be difficult for real cameras. The improvement can be achieved if linear 12-bit RAW images are used as of- fered by modern mid-class and professional cameras. The knowledge of exposure time positively affects the radiomet- ric quality of the composed high dynamic range (HDR) im- age. This knowledge also helps in registration of differently exposed hand held shots. This contribution presents a new method for estimating exposure times from the histograms of images captured using a linear response camera or gen- erated from a RAW image. The presented method does not require spatially aligned images. The actual process of HDR image composition needs perfectly aligned images on its in- put. We present a method for registering differently exposed images captured with a hand held camera. The presented registration method enables capture of HDR images without the need of mounting a camera on the tripod. The methods are implemented in Matlab and tested on real data.

A Simple, Effective System for Automated Capture of High Dynamic Range Images

Abstract: In recent years, high dynamic range imaging (HDRI) has become a topic of intense research interest in the fields of computer vision, computer graphics, and commercial visualization. Yet, despite the inherent limitations of traditional low dynamic range imaging (LDRI) and the emerging need for HDRI in many applications, existing systems for HDR image capture still remain proprietary, expensive, or manually-guided. All of these factors limit the availability of effective HDRI tools, thereby restricting studies which could otherwise benefit from this technology. To help alleviate this problem, we introduce a system and method for automated capture of high-quality, high-range images using commercially-available digital cameras. We report results comparing acquisition time, image resolution, and dynamic range and show these factors to compare very favorably both to traditional manual capture methods and to specialized HDRI systems developed commercially.

High Dynamic Range Display Adopting High Dynamic Range Imaging Technique

Abstract: Technique of high dynamic range imaging (HDRI) was introduced into conventional high dynamic range display (HDRD). Sharpness of image was further enhanced by improving local contrast ratio in the HDRI-based high dynamic range display.

Automatic High Dynamic Range and Resolution Imaging for 2DGE Images

Abstract: 2-Dimensional Gel Electrophoresis Image (2DGE) has been commonly used by biologists. Biologists only take one image for each 2D gel in traditional, and separate complex protein mixtures in the image. The image took by traditional way shall loss some of proteins that are existing in the 2D gel originally. To reduce the loss, we propose a High Dynamic Range and Resolution (HDRR) image technique in this paper. HDRR will preserve whole protein spots by taking multiple luminance and resolution images. We can change resolutions and luminance of HDRR image immediately. In traditionally, the generation of a HDRR image needs to scan a 2D gel many times in different resolutions and luminance. However, this way will be time-consuming in scanning and probably causes manual carelessness. The other contribution of the paper is our HDRR method can scan different resolutions and luminance as well as integrating these images in HDRR format automatically. The automatic method mentioned in this paper saves 2/3 time of traditional way in scanning. This is the other contribution of this paper.

Remapping the pupil

Abstract: Correction of the influence of phase corrugations in the pupil plane is a fundamental issue in achieving high dynamic range imaging. We present here an imaging system which, thanks to non-redundant pupil remapping and spatial filtering, allows a perfect determination of the Optical Transfer Function. We do show that such a system would allow image reconstruction free from phase perturbations, photon noise limited, and with high dynamic range.