Tone mapping

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

HDR-NeRF: High Dynamic Range Neural Radiance Fields

Abstract: We present High Dynamic Range Neural Radiance Fields (HDR-NeRF) to recover an HDR radiance field from a set of low dynamic range (LDR) views with different exposures. Using the HDR-NeRF, we are able to generate both novel HDR views and novel LDR views under different exposures. The key to our method is to model the simplified physical imaging process, which dictates that the radiance of a scene point transforms to a pixel value in the LDR image with two implicit functions: a radiance field and a tone mapper. The radiance field encodes the scene radiance (values vary from 0 to $+\infty$ ), which outputs the density and radiance of a ray by giving corresponding ray origin and ray direction. The tone mapper models the mapping process that a ray hitting on the camera sensor becomes a pixel value. The color of the ray is predicted by feeding the radiance and the corresponding exposure time into the tone mapper. We use the classic volume rendering technique to project the output radiance, colors and densities into HDR and LDR images, while only the input LDR images are used as the supervision. We collect a new forward-facing HDR dataset to evaluate the proposed method. Experimental results on synthetic and real-world scenes validate that our method can not only accurately control the exposures of synthesized views but also render views with a high dynamic range.

Dynamic tone grouping and encoding for multi-carrier quadrature amplitude in OFDM

Abstract: A method of dynamic tone grouping (DTG) used by a transmitter in a wireless OFDM system is proposed. First, a sequence of coded and interleaved bits is de-multiplexed into a number of bit-streams. Each bit-stream is mapped into a sequence of QAM symbols, which are grouped into non-overlapping sets of QAM symbols. Unitary transformation is then applied on the QAM symbols to produce groups of complex signals. Finally, the complex signals are dynamically mapped to subcarrier groups based on tone mapping information to improve link performance. The tone mapping information is derived from information associated with each OFDM subcarrier, such as channel state information (CSI). The OFDM subcarriers are grouped into subcarrier groups according to the tone mapping information such that the channel quality of each subcarrier group is balanced. In addition, the tone mapping information is efficiently encoded and transmitted to/from a corresponding receiver.

Real-time temporally coherent local HDR tone mapping

Abstract: Subjective studies showed that most HDR video tone mapping operators either produce disturbing temporal artifacts, or are limited in their local contrast reproduction capability. Recently, both these issues have been addressed by a novel temporally coherent local HDR tone mapping method, which has been shown, both qualitatively and through a subjective study, to be advantageous compared to previous methods. However, this method's high-quality results came at the cost of a computationally expensive workflow that could only be executed offline. In this paper, we present a modified algorithm which builds upon the previous work by redesigning key components to achieve real-time performance. We accomplish this by replacing the optical flow based per-pixel temporal coherency with a tone-curve-space alternative. This way we eliminate the main computational burden of the original method with little sacrifice in visual quality.

Visual sensitivity correlated tone reproduction for low dynamic range images in the compression field

Abstract: An image toning method for low dynamic range image compression is presented. The proposed method inserts tone mapping into JPEG baseline instead of postprocessing. First, an image is decomposed into detail, base, and surrounding components in terms of the discrete cosine transform coefficients. Subsequently, a luminance-adaptive tone mapping based on the human visual sensitivity properties is applied. In addition, compensation modules are added to enhance the visually sensitive factors, such as saturation, sharpness, and gamma. A comparative study confirms that the transmitted compression images have good image quality.

JPEG XT Image Compression with Hue Compensation for Two-Layer HDR Coding

Abstract: We propose a novel JPEG XT image compression with hue compensation for two-layer HDR coding. LDR images produced from JPEG XT bitstreams have some distortion in hue due to tone mapping operations. In order to suppress the color distortion, we apply a novel hue compensation method based on the maximally saturated colors. Moreover, the bitstreams generated by using the proposed method are fully compatible with the JPEG XT standard. In an experiment, the proposed method is demonstrated not only to produce images with small hue degradation but also to maintain well-mapped luminance, in terms of three kinds of criterion: TMQI, hue value in CIEDE2000, and the maximally saturated color on the constant-hue plane.