Tone mapping

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

Visual acuity-adaptive detail enhancement and shadow noise reduction for iCAM06-based HDR imaging

Abstract: An image appearance model is extremely useful for high-dynamic-range image (HDRI) rendering. However, the base–detail separation and the tone compression process for tonal control cause degradations in image quality. This study focuses on the de-saturation, reduced contrast, and noise problems in dark regions that occur through HDRI-rendering. First, we discuss de-saturation compensation using a bilateral filter that is based on the visual acuity characteristics of various illuminant levels. The edge stop function of the bilateral filter in iCAM06 is adaptively modified according to the illuminant information. Second, to reduce the magnified noise in the dark regions caused by tone mapping, the shadow regions are detected by an object’s intensity and illuminant level, and then the noise of the detected regions is reduced using a luminance-adaptive coring function. Finally, we confirmed the enhanced color saturation, image contrast, and reduced noise in shadow regions through the application of the proposed methods.

Brightness control for spatially adaptive tone mapping of high dynamic range (HDR) images

Abstract: Techniques are provided for spatially adaptive tone mapping with dynamic brightness control. A methodology implementing the techniques according to an embodiment includes converting luminance data, from a received HDR image, to a logarithm domain and decomposing the converted data into a base layer, and one or more detail layers. The method also includes adjusting the layers, through shifting and scaling of the base layer and scaling of the detail layers, to map the amplitude data into a selected range. The method further includes converting the adjusted layers from the logarithm domain to a linear domain and calculating a tone compression parameter based on statistics of the adjusted log domain base layer. The statistics are associated with brightness of the received image. The method further includes applying a global tone compression function, based on the tone compression parameter, to the converted linear domain base layer to generate compressed linear domain layers.

HVS based histogram adjustment for tone mapping

Abstract: Global tone mapping operators (TMOs) are better in preserving the naturalness and relative illumination of the HDR scene compared to the local TMOs. However, they cannot preserve the details like the local TMOs. We propose a human visual system (HVS) based histogram method for global tone mapping, which can better preserve the details than the existing global TMOs. Our method can be incorporated to all histogram based global methods. We compare our results with traditional histogram adjustment by Ward et al. [Larson97] and photographic TMO [Reinhard2002], and in most of the cases our method is better in preserving the details of the input HDR images.

Method for enhancing vehicle-mounted night vision image

Abstract: The invention provides a method for enhancing a vehicle-mounted night vision image. According to the method, an image of the same scene is simultaneously acquired by a plurality of cameras arranged at different positions; multi-image fusion is adopted; after a series of treatments of image data decoding, filtering, registration, tone mapping and histogram modification are carried out, a single unclear image is obviously enhanced after being processed by the adoption of the method; the vehicle-mounted night vision image can be effectively enhanced; the dynamic range of the vehicle-mounted night vision image is obviously improved; light spots caused by overexposure in the night vision image disappear or are obviously weakened; surrounding information of hard light is clear; front and surrounding information can be clearly displayed by a night vision system; and a driver can clearly see the front and surrounding environment. Moreover, by a DSP (Digital Signal Processing) and FPGA (Field Programmable Gate Array) combination hardware implementing method, the image registration operation is implemented on a FPGA, the image tone mapping operation is carried out in a DSP and the speed and the real-time performance of executing the method are improved.

HMD-TMO: A Tone Mapping Operator for 360\(^\circ \) HDR Images Visualization for Head Mounted Displays

Abstract: We propose a Tone Mapping Operator, denoted HMD-TMO, dedicated to the visualization of 360\(^\circ \) High Dynamic Range images on Head Mounted Displays. The few existing studies about this topic have shown that the existing Tone Mapping Operators for classic 2D images are not adapted to 360\(^\circ \) High Dynamic Range images. Consequently, several dedicated operators have been proposed. Instead of operating on the entire 360\(^\circ \) image, they only consider the part of the image currently viewed by the user. Tone mapping a part of the 360\(^\circ \) image is less challenging as it does not preserve the global luminance dynamic of the scene. To cope with this problem, we propose a novel tone mapping operator which takes advantage of both a view-dependant tone mapping that enhances the contrast, and a Tone Mapping Operator applied to the entire 360\(^\circ \) image that preserves global coherency. Furthermore, we present a subjective study to model lightness perception in a Head Mounted Display.