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 high dynamic range rendering pipeline for interactive applications: In search for perceptual realism

Abstract: Realistic images can be computed at interactive frame rates for Computer Graphics applications. Meanwhile, High Dynamic Range (HDR) rendering has a growing success in video games and virtual reality applications, as it improves the image quality and the player’s immersion feeling. In this paper, we propose a new method, based on a physical lighting model, to compute in real time a HDR illumination in virtual environments. Our method allows to re-use existing virtual environments as input, and computes HDR images in photometric units. Then, from these HDR images, displayable 8-bit images are rendered with a tone mapping operator and displayed on a standard display device. The HDR computation and the tone mapping are implemented in OpenSceneGraph with pixel shaders. The lighting model, together with a perceptual tone mapping, improves the perceptual realism of the rendered images at low cost. The method is illustrated with a practical application where the dynamic range of the virtual environment is a key rendering issue: night-time driving simulation.

A GPU-friendly method for high dynamic range texture compression using inverse tone mapping

Abstract: In recent years, High Dynamic Range Textures (HDRTs) have been frequently used in real-time applications and video-games to enhance realism. Unfortunately, HDRTs consume a considerable amount of memory, and efficient compression methods are not straightforward to implement on modern GPUs. We propose a framework for efficient HDRT compression using tone mapping and its dual, inverse tone mapping. In our method, encoding is performed by compressing the dynamic range using a tone mapping operator followed by a traditional encoding method for low dynamic range imaging. Our decoding method, decodes the low dynamic range image and expands its range with the inverse tone mapping operator. We present results using the Photographic Tone Reproduction tone mapping operator and its inverse encoded with S3TC running in real-time on current programmable GPU-hardware resulting in compressed HDRTs at 4--8 bits per pixel (bpp), using a fast shader program for decoding. We show how our approach is favorable compared to other existing methods.

Rendering high dynamic range images by using integrated global and local processing

Abstract: We propose a new and effective tone reproduction technique that preserves the visibility, contrast, and natural impression of scenes when rendering high dynamic range images on conventional low dynamic range display devices. The method is simple and easy to implement. Our new approach uses a modified mapping function that takes into account the block-level log-average, as well as the log-average of the whole image. This allows for increased visibility in dark regions. For those images with sharp edges that may cause a halo effect, the halo effect can be reduced by using bilateral filtering when the block-level log-average is computed. Furthermore, the local details of the image can be enhanced by using a median filter. Experimental results show that the technique gives satisfactory results for a variety of images and avoids common artefacts, such as halos, gradient reversals, and the loss of local contrast. In particular, our method produces excellent results when an image has both dark and bright regions due to new block-level processing during tone mapping.

Collaborative color calibration for multi-camera systems

Abstract: This paper proposes a collaborative color calibration method for multi-camera systems. The multi-camera color calibration problem is formulated as an overdetermined linear system, in which a dynamic range shaping is incorporated to ensure the high contrasts for captured images. The cameras are calibrated with the parameters obtained by solving the linear system. For non-planar multi-camera systems, we design a novel omnidirectional color checker and present a method for establishing global correspondences to facilitate automatic color calibration without manual adjustment. According to experimental results on both synthetic and real-system datasets, the proposed method shows high performance in achieving inter-camera color consistency and high dynamic range. Thanks to the generality of the linear system formulation and the flexibility of the designed color checker, the proposed method is applicable to various multi-camera systems.

On-the-fly tone mapping for backward-compatible high dynamic range image/video compression

Abstract: In this paper, we propose a real-time tone-mapping scheme for backward compatible high dynamic range (HDR) video compression. The appropriate choice of a tone-mapping operator (TMO) can significantly improve the HDR quality reconstructed from a low dynamic range (LDR) version. We develop a statistical model that approximates the mean square error (MSE) distortion resulting from the combined processes of tone-mapping and compression. Using this model, we formulate a numerical optimization problem to find the tone-curve that minimizes the expected MSE in the reconstructed HDR sequence. We then simplify the developed model in order to reduce the computational complexity of the optimization problem to a closed-form solution. Performance evaluations show that the proposed methods provide superior performance in terms of HDR MSE and SSIM compared to existing tone-mapping schemes. It is also shown that the LDR image quality resulting from the proposed methods matches that produced by perceptually-based TMOs.