Tone mapping

About: Tone mapping is a research topic. Over the lifetime, 1713 publications have been published within this topic receiving 48490 citations.

Dynamic Range Reduction of SAR Image via Global Optimum Entropy Maximization With Reflectivity-Distortion Constraint

Abstract: The visualization of synthetic aperture radar (SAR) images plays a critical role in remote sensing applications. To effectively obtain the image suitable for human observation, this paper introduces a new SAR image visualization algorithm to map the high dynamic range SAR amplitude values to low dynamic range displays via reflectivity distortion preserved entropy maximization. Its designed objective is to present the maximal amount of information content in the displayed image, and being optimal in an information theoretical sense, as well as restricting the upper bound of the reflection distortion caused by tone mapping. The resulting optimization problem can be graph theoretically modeled as a $K$ -edges maximum weight path problem in a directed acyclic graph, and it can be solved efficiently by dynamic programming in real time. Empirical evidences are provided to demonstrate the superior visual quality obtained by our new visualization technique.

Single Layer Progressive Coding for High Dynamic Range Videos

Abstract: There are different kinds of high dynamic range (HDR) displays in the market today. These displays have different HDR specifications, like, pealddark brightness levels, electro-optical transfer functions (EOTF), color spaces etc. For the best visual experience on a given HDR screen, colorists have to grade videos for that specific display’s luminance range. Uut simultaneous transmission of multiple video bitstreams graded at different luminance ranges, is inefficient in terms of network utility and server storage. To overcome this problem, we propose transmitting our progressive metadata with a base layer video bitstream. This embedding allows different overlapping portions of metadata to scale the base video to progressively wider luminance ranges. Our progressive metadata format provides a significant design improvement over the existing architectures, preserves colorist intent at all the supported brightness ranges and still keeps the bandwidth or storage overhead minimal.

System and method for processing image data using image signal processor having final processing logic

Abstract: FIELD: physics, computer engineering.SUBSTANCE: invention relates to digital imaging devices and particularly to systems and a method of processing image data obtained using the image sensor of a digital imaging device. An image signal processing system includes a pixel final processing unit, a pixel preprocessing unit and a pixel processing conveyor. The final processing unit receives pixel data of image brightness/chrominance after processing by one of the preprocessing unit and processing conveyor. The final processing unit is configured to apply a facial detection operation, local tone mapping, brightness, contrast and colour control, as well as scaling. The final processing unit also includes a final statistics processing unit which collects frequency statistics. The frequency statistics are provided to an encoder and used to determine sampling parameters to be applied to an image frame.EFFECT: improved outward appearance of an image, achieved by increasing definition of the image without noise or artefacts.20 cl, 142 dwg, 5 tbl

Improving the Tone Mapping Operators by Using a Redefined Version of the Luminance Channel

Abstract: Tone mapping operators (TMOs) convert high dynamic range (HDR) images to low dynamic range (LDR) images and are important because of the limitations of many standard display devices. Even though the quality of the resulting LDR image mostly depends on TMO parameter values, in this paper it is shown that it can be further improved by using alternative definitions of the luminance channel, which TMOs process. A new model of the luminance channel calculation that increases the resulting LDR image quality is also proposed. The main advantage of the new model is that the TMOs that produce results of lower quality can be made to produce results of significantly higher quality.

Embedding high dynamic range tone mapping in JPEG compression

Abstract: A method that integrates tone mapping for high dynamic range (HDR) gray-scale images with JPEG compression is proposed. The tone mapping operator (TMO) is block-based, and structured so that the same discrete cosine transform (DCT) that is used for the JPEG compression serves to complete a major part of the tone-mapping operation. Simulations have been done on high dynamic range images from the Debevec library. Experimental results show the technique successfully tone maps and compresses simultaneously; the number of bits per pixel is reduced from 32 to an average of 0.67 by the compression, with an average PSNR of 56.3 dB for the compressed tone-mapped images compared to images that have been only tone-mapped. The output of the proposed method is an image that requires only limited storage space, and can be decompressed with a standard JPEG decoder.