High Dynamic Range Processing Research Articles

Optimizing immunofluorescence with high-dynamic-range imaging to enhance PD-L1 expression evaluation for 3D pathology assessment from NSCLC tumor tissue

Assessing programmed death ligand 1 (PD-L1) expression through immunohistochemistry (IHC) is the golden standard in predicting immunotherapy response of non-small cell lung cancer (NSCLC). However, observation of heterogeneous PD-L1 distribution in tumor space is a challenge using IHC only. Meanwhile, immunofluorescence (IF) could support both planar and three-dimensional (3D) histological analyses by combining tissue optical clearing with confocal microscopy. We optimized clinical tissue preparation for the IF assay focusing on staining, imaging, and post-processing to achieve quality identical to traditional IHC assay. To overcome limited dynamic range of the fluorescence microscope’s detection system, we incorporated a high dynamic range (HDR) algorithm to restore the post imaging IF expression pattern and further 3D IF images. Following HDR processing, a noticeable improvement in the accuracy of diagnosis (85.7%) was achieved using IF images by pathologists. Moreover, 3D IF images revealed a 25% change in tumor proportion score for PD-L1 expression at various depths within tumors. We have established an optimal and reproducible process for PD-L1 IF images in NSCLC, yielding high quality data comparable to traditional IHC assays. The ability to discern accurate spatial PD-L1 distribution through 3D pathology analysis could provide more precise evaluation and prediction for immunotherapy targeting advanced NSCLC.

High Dynamic Range Image Processing for Retinal Color Fundus Photography.

Color fundus photography is an important imaging modality that is currently limited by a narrow dynamic range. We describe a post-image processing technique to generate high dynamic range (HDR) retinal images with enhanced detail. This was a retrospective, observational case series evaluating fundus photographs of patients with macular pathology. Photographs were acquired with three or more exposure values using a commercially available camera (Topcon 50-DX). Images were aligned and imported into HDR processing software (Photomatix Pro). Fundus detail was compared between HDR and raw photographs. Sixteen eyes from 10 patients (5 male, 5 female; mean age 59.4 years) were analyzed. Clinician graders preferred the HDR image 91.7% of the time (44/48 image comparisons), with good grader agreement (81.3%, 13/16 eyes). HDR fundus imaging is feasible using images from existing fundus cameras and may be useful for enhanced visualization of retinal detail in a variety of pathologic states. [Ophthalmic Surg Lasers Imaging Retina 2024;55:263-269.].

A Display-Independent Quality Assessment for HDR Images

High Dynamic Range (HDR) images improve visual quality by representing a wide range of luminance in real world. HDR Image Quality Assessment (IQA) is essential in HDR processing technologies. This work focus on the IQA for the HDR applications represented by HDR compression. Towards designing IQA for these tasks, user-end display information should not be considered, given that these tasks only focus on the media intrinsic features. However, most existing HDR metrics are associated with display luminance, hence they can not handle IQA during HDR processing. In this work, we find that it is possible to evaluate HDR image quality without prior knowledge of luminance for display. Based on this, we proposed a low complexity Display-Independent Gradient Magnitude Similarity (DIGMS) metric. Experimental results demonstrate that the proposed DIGMS outperforms the state-of-the-arts in HDR IQA. This work opens up a new perspective for designing IQA algorithms for HDR images.

Local contrast-enhanced MR images via high dynamic range processing.

PurposeTo develop a local contrast‐enhancing and feature‐preserving high dynamic range (HDR) image processing algorithm for multichannel and multisequence MR images of multiple body regions and tissues, and to evaluate its performance for structure visualization, bias field (correction) mitigation, and automated tissue segmentation.MethodsA multiscale‐shape and detail‐enhancement HDR‐MRI algorithm is applied to data sets of multichannel and multisequence MR images of the brain, knee, breast, and hip. In multisequence 3T hip images, agreement between automatic cartilage segmentations and corresponding synthesized HDR‐MRI series were computed for mean voxel overlap established from manual segmentations for a series of cases. Qualitative comparisons between the developed HDR‐MRI and standard synthesis methods were performed on multichannel 7T brain and knee data, and multisequence 3T breast and knee data.ResultsThe synthesized HDR‐MRI series provided excellent enhancement of fine‐scale structure from multiple scales and contrasts, while substantially reducing bias field effects in 7T brain gradient echo, T1 and T2 breast images and 7T knee multichannel images. Evaluation of the HDR‐MRI approach on 3T hip multisequence images showed superior outcomes for automatic cartilage segmentations with respect to manual segmentation, particularly around regions with hyperintense synovial fluid, across a set of 3D sequences.ConclusionThe successful combination of multichannel/sequence MR images into a single‐fused HDR‐MR image format provided consolidated visualization of tissues within 1 omnibus image, enhanced definition of thin, complex anatomical structures in the presence of variable or hyperintense signals, and improved tissue (cartilage) segmentation outcomes.

The technology behind the exceptional visual experience via high dynamic range

High dynamic range (HDR) technology is rapidly changing today's video landscape by offering spectacular visual experiences. The development in display technology to support higher luminance levels for commercial and consumer electronic devices such as TVs, smartphones, projectors etc., has created an exponential demand for delivering HDR content to viewers. The essential component of the HDR technology is “expanded contrast,” which allows richer black levels and enhanced brightness, providing dramatic contrast that reveals finer details. The use of “wide color gamut” allows wider color spectrum and richer colors providing aesthetically pleasing true-to-life feel. Such visual enhancements clearly establish HDR as one of the most significant upcoming video technologies.In this paper, we review major technical advances in this exciting field of study. Quantization of HDR signals is reviewed in the context of transfer functions that convert optical signals to electrical signals and vice versa. They mainly consist of Perceptual Quantization and Hybrid-Log-Gamma approaches. Compression of HDR content is another broad area of study involving several coding approaches, often categorized in terms of backward-compatibility and single/dual layer methods. Some key industry applications of HDR processing systems are also discussed, followed by some future directions of HDR technology.

Evidence theory for high dynamic range reconstruction with linear digital cameras

With the advent of the digital camera, a common popular imaging processing is high dynamic range (HDR) that aims to overcome the technological limitations of the irradiance sensor dynamic range. In this paper, we will present a new method to combine low dynamic range images (LDR) for HDR processing. This method is based on the theory of evidence. Without a prior knowledge of the sensor intrinsic parameters and no extra data, it allows to locally maximizing the signal to noise ratio over the entire acquisition dynamic. In addition, our method is less sensitive to object or people in motion into the scene that are causing ghost-like artifacts with the conventional methods. This technique require that the camera be absolutely still between exposures or need a translational alignment. Simulation and experimental results are presented to demonstrate both the accuracy and efficiency of our algorithm.

HDR-ARtiSt: an adaptive real-time smart camera for high dynamic range imaging

This paper describes a complete FPGA-based smart camera architecture named HDR-ARtiSt (High Dynamic Range Adaptive Real-time Smart camera) which produces a real-time high dynamic range (HDR) live video stream from multiple captures. A specific memory management unit has been defined to adjust the number of acquisitions to improve HDR quality. This smart camera is built around a standard B&W CMOS image sensor and a Xilinx FPGA. It embeds multiple captures, HDR processing, data display and transfer, which is an original contribution compared to the state-of-the-art. The proposed architecture enables a real-time HDR video flow for a full sensor resolution (1.3 Mega pixels) at 60 frames per second.

Simultaneous High Dynamic Range and Superresolution Imaging without Regularization

Modern digital camera sensors capture only a limited amplitude and frequency range of the irradiance of a scene. A recent trend is to acquire and combine multiple images to raise the quality of the final image. Multi-image techniques are used in high dynamic range processing, where multiple exposure times are used to reconstruct the full range of irradiance. With multi-image superresolution, the difference between sampling grids caused by the motion of the camera is used to generate a high resolution image. It is possible to combine these two processes into one to generate a superresolved image with a full dynamic range. In this paper, we study the reconstruction error of high dynamic range superresolution imaging without regularization, under an affine motion hypothesis. From this study, we deduce a strategy for choosing the number of images and the exposure times, which makes the unregularized problem well conditioned. With these acquisition parameters, if the affine motion hypothesis holds and sufficiently long exposure time is available, the recovery of all the amplitude and frequency content of the scene irradiance is guaranteed.

High Dynamic Range Processing for Magnetic Resonance Imaging

PurposeTo minimize feature loss in T1- and T2-weighted MRI by merging multiple MR images acquired at different TR and TE to generate an image with increased dynamic range.Materials and MethodsHigh Dynamic Range (HDR) processing techniques from the field of photography were applied to a series of acquired MR images. Specifically, a method to parameterize the algorithm for MRI data was developed and tested. T1- and T2-weighted images of a number of contrast agent phantoms and a live mouse were acquired with varying TR and TE parameters. The images were computationally merged to produce HDR-MR images. All acquisitions were performed on a 7.05 T Bruker PharmaScan with a multi-echo spin echo pulse sequence.ResultsHDR-MRI delineated bright and dark features that were either saturated or indistinguishable from background in standard T1- and T2-weighted MRI. The increased dynamic range preserved intensity gradation over a larger range of T1 and T2 in phantoms and revealed more anatomical features in vivo.ConclusionsWe have developed and tested a method to apply HDR processing to MR images. The increased dynamic range of HDR-MR images as compared to standard T1- and T2-weighted images minimizes feature loss caused by magnetization recovery or low SNR.

HDR imaging evaluation of a NT-proBNP test with a mobile phone

The determination of NT-proBNP levels is key for the monitoring of patients with diagnosed heart failure and it is a routine measurement typically performed at health care centers, which would benefit from decentralized alternatives. Here we investigate the quantitative evaluation of a well-established NT-proBNP test using a standard mobile phone (Nokia 6720) as measuring platform rather than a dedicated instrument. A Java ME software developed for this application controls the illumination and imaging of the proBNP test under defined time intervals, which enables the composition of multi-exposure sets that are processed as high dynamic range (HDR) images for contrast enhancement. The results show that HDR processing significantly increases the sensitivity and resolution of the technique achieving a performance within the diagnostics range. These results demonstrate the feasibility to exploit a ubiquitous device to decentralize the evaluation of a routine test and identify key processing alternatives to bring the performance of such systems within the diagnostics range.

Mobile phone analysis of NT-proBNP using high dynamic range (HDR) imaging

In this work we demonstrate the evaluation of a commercial NT-proBNP test using a standard mobile phone as a measuring platform. A Java ME software developed for this application controls the illumination and imaging of the NT-proBNP test under defined time intervals, enabling the compositions of multi-exposure sets that can be processed as high dynamic range (HDR) images for contrast enhancement. The results show that HDR processing significantly increases resolution and detection range, which makes the phone-based evaluation a promising possibility.

Applications of high‐frequency radar

Efforts to extend radar range by an order of magnitude with use of the ionosphere as a virtual mirror started after the end of World War II. A number of HF radar programs were pursued, with long‐range nuclear burst and missile launch detection demonstrated by 1956. Successful east coast radar aircraft detect and track tests extending across the Atlantic were conducted by 1961. The major obstacles to success, the large target‐to‐clutter ratio and low signal‐to‐noise ratio, were overcome with matched filter Doppler processing. To search the areas that a 2000 nautical mile (3700 km) radar can reach, very complex and high dynamic range processing is required. The spectacular advances in digital processing technology have made truly wide‐area surveillance possible. Use of the surface attached wave over the oceans can enable HF radar to obtain modest extension of range beyond the horizon. The decameter wavelengths used by both skywave and surface wave radars require large physical antenna apertures, but they have unique capabilities for air and surface targets, many of which are of resonant scattering dimensions. Resonant scattering from the ocean permits sea state and direction estimation. Military and commercial applications of HF radar are in their infancy.