Good Image Fidelity Research Articles

An Imperceptible Watermarking Scheme for Medical Image Tamper Detection

One of the important issues in telemedicine field refers to an advanced secure communication. Digital image watermarking is an ideal solution since it protects the electronic patient information’s from unauthorized access. This paper presents a novel blind fragile-based image watermarking scheme in spatial domain that merges Speed Up Robust Features (SURF) descriptor with the well-known Weber Descriptors (WDs) and Arnold algorithm. It provides a good way for enhancing the image quality and time complexity for medical data integrity. Firstly, the watermark image is shuffled using Arnold chaotic map. Secondly, the SURF technique is practiced to Region of Interest (ROI) of the medical image and then the blocks around the SURF points are selected to insert the watermark. Finally, the watermark is encrusted and extracted using WDs. Experimental results show good image fidelity with the shortest execution time to ensure medical images integrity.

A novel blind medical image watermarking scheme based on Schur triangulation and chaotic sequence

AbstractImage watermarking is a potentially effective and powerful solution for multimedia security. It is a technique that plays a fundamental role in protecting copyright, proofing ownership, and helps to authenticate sensitive data. Watermarking can cause a decrease in image quality, especially when it comes to medical images. This could provoke false diagnoses, which can lead to serious consequences on the patient's health. In fact, it becomes necessary to think for new more imperceptible, secure watermarking techniques. To provide such techniques, we proposed a novel blind watermarking scheme for medical images, based on Schur decomposition and chaotic sequence (CS). An efficient chaotic method is applied on the watermark and the cover image to obtain encrypted images divided into subblocks. A decomposition based on Schur is utilized to embed the encrypted watermark bits in the cyphered cover image blocks. The same CS is applied to extract the original watermark. We compared the proposed technique with other watermarking schemes. The experimentation results demonstrate that the suggested method achieving good image fidelity and acceptable robustness.

Multiple Blind Watermarking Framework for Security and Integrity of Medical Images in E-Health Applications

Nowadays, e-health applications carry the most advanced information and communication technologies for ensuring quality, remote healthcare services, and support diagnostics. These applications are sharing and transmitting of medical data over the internet, which makes them serious targets for alteration and illegal access. Image watermarking presents a compelling solution for protecting patient's information and ensures medical image integrity. This paper gives a new secure framework to protect medical data based on blind multiple watermarking schemes. The proposed approach consists of combining LWT (lifting wavelet transform), QR decomposition, and Arnold chaotic map in transform domain for the first watermark, while for the second watermark is encrusted in the spatial domain. During the de-watermarking process, both extracted watermarks are compared to detect any alterations during transmitting. The experimentation results demonstrate that the suggested method achieves good image fidelity and alters detection and robustness contra different kinds of attacks.

Cassiopeia A, Cygnus A, Taurus A, and Virgo A at ultra-low radio frequencies

Context. The four persistent radio sources in the northern sky with the highest flux density at metre wavelengths are Cassiopeia A, Cygnus A, Taurus A, and Virgo A; collectively they are called the A-team. Their flux densities at ultra-low frequencies (< 100 MHz) can reach several thousands of janskys, and they often contaminate observations of the low-frequency sky by interfering with image processing. Furthermore, these sources are foreground objects for all-sky observations hampering the study of faint signals, such as the cosmological 21 cm line from the epoch of reionisation. Aims. We aim to produce robust models for the surface brightness emission as a function of frequency for the A-team sources at ultra-low frequencies. These models are needed for the calibration and imaging of wide-area surveys of the sky with low-frequency interferometers. This requires obtaining images at an angular resolution better than 15″ with a high dynamic range and good image fidelity. Methods. We observed the A-team with the Low Frequency Array (LOFAR) at frequencies between 30 MHz and 77 MHz using the Low Band Antenna system. We reduced the datasets and obtained an image for each A-team source. Results. The paper presents the best models to date for the sources Cassiopeia A, Cygnus A, Taurus A, and Virgo A between 30 MHz and 77 MHz. We were able to obtain the aimed resolution and dynamic range in all cases. Owing to its compactness and complexity, observations with the long baselines of the International LOFAR Telescope will be required to improve the source model for Cygnus A further.

Image steganography based on digital holography and saliency map

A gray-level intensity image can be employed as a host image for hiding a watermark image to protect information security. Past research works demonstrate that a gray-level hidden image can be embedded into the host image by a digital phase-only holography method. However, the fidelity of retrieved watermark image from the host image is not very satisfactory and the host image quality is degraded due to the insertion of external data bits, especially when observers focus on the saliency regions in the host image. To address this problem, we propose a steganography method based on digital holography and the saliency map of the host image. First, we calculate the hidden capacity (number of bits to be replaced) for each host image pixel based on the weighted sum of pixel intensity and saliency value. Next, a multilevel phase-only digital hologram of the watermark image will be calculated by the Gerchberg–Saxton method under the constraint of the hidden capacity of host image. Finally, we embedded the multilevel phase-only digital hologram into the host image by replacing a corresponding number of bits in each pixel. In this way, the host image can preserve good image fidelity for its saliency regions even if we hide a large amount of digital hologram data into the host image. The experimental results show that the quality of retrieved watermark image from the host image and the quality of saliency regions in the watermarked host image, in our proposed scheme, are superior to the state-of-the-art works reported.

Characterizing and solving imaging challenges in thick resists for wafer and panel based lithography applications

Abstract Increasing volume using larger substrates with decreasing process margins continues to create new challenges for advanced packaging applications. Key step and repeat camera technology continues evolving for the mass production of microstructures used for 2.5D and 3D technologies. Printing dense arrays of smaller features with high aspect ratios requires higher sidewall angles in thick photoresists and polyimides. To help solve these imaging challenges we have leveraged resist modeling software and guided the adjustment of optical parameters needed for better performance. Higher contrast films have also been evaluated to help achieve the improvements in performance needed. Resist models that can include the effects of flare have been critical to understand the requirement for printing in thick negative resists and has aided in printing features on varying topography and film thicknesses. Special chucks help improve the flatness of warped wafers and real-time auto-focusing provides good image fidelity. Printing microstructures over larger formats with higher throughput has been accomplished using large magnification adjustment for improving overlay and validated by characterizing image placement errors over large substrates. Examples of resist models that are created using resist parameters and optimized using SEM images of printed features are compared. Extrapolations of the resist models have shown that guide improvements can be achieved by varying optical parameters. SEM images confirm that the modeled result of the optimal solution was achieved. Reduction in large substrate overlay error was achieved after the stage corrections were applied. Examples show that topographical errors of warped wafers can be reduced and how real-time auto-focusing for each exposure minimizes focus errors.

A Brief Update on the CMZoom Survey

AbstractThe inner few hundred parsecs of the Milky Way, the Central Molecular Zone (CMZ), is our closest laboratory for understanding star formation in the extreme environments (hot, dense, turbulent gas) that once dominated the universe. We present an update on the first large-area survey to expose the sites of star formation across the CMZ at high-resolution in submillimeter wavelengths: the CMZoom survey with the Submillimeter Array (SMA). We identify the locations of dense cores and search for signatures of embedded star formation. CMZoom is a three-year survey in its final year and is mapping out the highest column density regions of the CMZ in dust continuum and a variety of spectral lines around 1.3 mm. CMZoom combines SMA compact and subcompact configurations with single-dish data from BGPS and the APEX telescope, achieving an angular resolution of about 4″ (0.2 pc) and good image fidelity up to large spatial scales.

Helicity multiplexed broadband metasurface holograms.

Metasurfaces are engineered interfaces that contain a thin layer of plasmonic or dielectric nanostructures capable of manipulating light in a desirable manner. Advances in metasurfaces have led to various practical applications ranging from lensing to holography. Metasurface holograms that can be switched by the polarization state of incident light have been demonstrated for achieving polarization multiplexed functionalities. However, practical application of these devices has been limited by their capability for achieving high efficiency and high image quality. Here we experimentally demonstrate a helicity multiplexed metasurface hologram with high efficiency and good image fidelity over a broad range of frequencies. The metasurface hologram features the combination of two sets of hologram patterns operating with opposite incident helicities. Two symmetrically distributed off-axis images are interchangeable by controlling the helicity of the input light. The demonstrated helicity multiplexed metasurface hologram with its high performance opens avenues for future applications with functionality switchable optical devices.

Imaging blood cells through scattering biological tissue using speckle scanning microscopy

We demonstrate imaging of blood cells enclosed in chicken skin tissue using speckle scanning microscopy (SSM). Clear images of multiple cells were obtained with subcellular resolution and good image fidelity, provided that the object dimension was smaller than the maximum scanning range of the speckle pattern. These results point to the potential and the challenges of using SSM technique for biological imaging.

MUSTANG 2: A Large Focal Plane Array for the 100 m Green Bank Telescope

This paper describes MUSTANG 2, a 338 element focal plane array that is being built for the Green Bank Telescope. Each element consists of a profiled feedhorn coupled to two transition edge sensor bolometers, one for each polarization. Initial deployment will be with 32 detectors, but once fully populated, MUSTANG 2 will be capable of mapping a \(8'\times 8'\) area to \(23~\upmu \)Jy in 1 h with good image fidelity on angular scales from \(9''\) to \(6'\). As well as an instrument overview, the choice of bandpass and the design of the feeds, detectors and readout are given.

65.3: Stencil Field‐Sequential‐Color Method on Locally Controlled Side‐lit Eco‐LCDs

AbstractTo develop a thin, high image quality, and low power consumption eco‐display, a novel backlight determination method called “Limited Backlight Signal Ratio” (LBSR) is proposed to applied in a side‐lit 180Hz Stencil‐FSC LCD. The point spread function of a side‐lit backlight division is optimized to maintain a 97% higher backlight luminance uniformity and good image fidelity. Simulation results indicate the optimal backlight division is 2×16 with color breakup suppression reach asymptotic end values. The experimental photos demonstrate the side‐lit LBSR 180Hz Stencil‐FSC method can suppress color breakup effectively and can increase image fidelity greatly. As a result, side‐lit LBSR 180Hz Stencil‐FSC method is promising for future side‐lit eco‐display applications.

29.3: RGBW 4‐in‐1 LEDs for Backlight System for Ultra‐Low Power Consumption Field‐Sequential‐Color LCDs

AbstractThe power consumption of field‐sequential‐color (FSC) LCDs is much lower than conventional LCDs. To further reduce the power consumption of FSC‐LCDs, high power efficiency white‐LED was added to RGB‐LED as a RGBW 4‐in‐1 LEDs. The gray part of image was generated by using a white‐LED instead of mixing of red, green, and blue LED. The remaining color part in the image was generated by using RGB‐LED. Base on the efficiency of white‐LED, power consumption of FSC‐LCDs could be further reduced while still maintaining good image fidelity.

ILT Approach for Compensating 3-D Mask Effects

As mask features scale to smaller dimensions, the so-called “3-D mask effects” which have mostly been neglected before, become important. This paper properly models the 3-D thick mask effects, and then analyses the object-based inverse lithography technique using a simulated annealing algorithm to determine the mask shapes that produce the desired on-wafer results. Evaluations against rigorous simulations show that the synthesized masks provide good image fidelity up to 0.94, and this approach gives improved accuracy and faster results than existing methods.