Tone mapping

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

Methods and apparatuses for tone mapping and inverse tone mapping

Abstract: A method of producing at least one output image signal representing, at least, a plurality of output luminance values in an output range of luminance values is disclosed. The method involves: identifying a mapping function based at least in part on a perceptually scaled distribution of a plurality of input luminance values in an input range of luminance values different from the output range of luminance values; transforming the plurality of input luminance values into respective perceptually scaled output luminance values according to the mapping function; transforming the perceptually scaled output luminance values into respective ones of the plurality of output luminance values; and producing the at least one output signal representing, at least, the plurality of output luminance values. Computer-readable media and apparatuses are also disclosed.

Tone-preserving contrast enhancement in images using rational tone mapping and constrained optimization

Abstract: In this paper, we propose tone-preserving contrast enhancement in images using rational tone mapping and constrained optimization. We first perform spike-removed histogram equalization (SRHE) for contrast enhancement to avoid over-enhancement caused by the conventional HE. We conduct rational tone mapping (RTM) with low-complexity to preserve the original tone continuity. Then, we formulate a constrained optimization problem consisting of the contrast enhancement and tone-preserving terms. By minimizing the objective function, we find the best trade-off between the two conflicting terms. Experimental results demonstrate that the proposed method enhances contrast in images while successfully preserving details, and outperforms state-of-the-art ones in both subjective and objective assessments.

High Dynamic Range Image Compression Based on Visual Saliency

Abstract: High dynamic range (HDR) image has larger luminance range than conventional low dynamic range (LDR) image, which is more consistent with human visual system (HVS). Recently, JPEG committee releases a new HDR image compression standard JPEG XT. It decomposes input HDR image into base layer and extension layer. However, this method doesn’t make full use of HVS, causing waste of bits on imperceptible regions to human eyes. In this paper, a visual saliency based HDR image compression scheme is proposed. The saliency map of tone mapped HDR image is first extracted, then is used to guide extension layer encoding. The compression quality is adaptive to the saliency of the coding region of the image. Extensive experimental results show that our method outperforms JPEG XT profile A, B, C, and offers the JPEG compatibility at the same time. Moreover, our method can provide progressive coding of extension layer.

System and method of tone mapping during single user and multiple user operating modes including transmissions respectively of ofdm symbols and ofdma symbols in a wlan

Abstract: A system including a direct current tone, guard tone, data tone allocation, mapping, and inverse Fourier transform (IFT) modules. The direct current tone module determines a number of direct current tones based on whether a network device is operating in a single user or multi-user mode. The guard tone module determines a number of guard tones based on whether the network device is operating in the single user or multi-user mode. The data tone allocation module determines a number of data tones based on the number of direct current and guard tones. The mapping module receives data and based on the number of data tones, maps the data to the data tones. The IFT module performs a frequency to time domain conversion of an output of the mapping module to generate orthogonal frequency division multiplexing (OFDM) symbols during the single user mode and OFDM access symbols during the multi-user mode.

Enhanced high dynamic-range image rendering using a surround map based on edge-adaptive layer blurring

Abstract: Many tone-mapping methods have developed efficient tone compression and local contrast enhancement techniques for high dynamic-range imaging. Local tone mapping enhances the image quality to reveal the details; however, it causes artefacts such as halos. Halo artefacts appear around the edges of an image and lead to deterioration in the overall image quality. Detail-base separation and multi-scale methods have been developed to reduce halo artefacts. Detail-base separation methods divide the image into a detail layer and base layer using an edge-preserving filter and process each layer independently. Multi-scale methods alleviate artefacts such as halos, noise, and awkward global toning using a weighted sum of single-scale images. These methods have several inherent problems including the complexity of the edge-preserving filter and multi-processing redundancy. Therefore, in this study, a novel surround map is presented to resolve halo artefacts and enhance local details in single-scale processing.