scholarly journals DCT Domain Detail Image Enhancement for More Resolved Images

Electronics ◽  
2021 ◽  
Vol 10 (20) ◽  
pp. 2461
Author(s):  
Seongbae Bang ◽  
Wonha Kim
Keyword(s):  
Signal Enhancement ◽  
Human Visual Perception ◽  
Dct Domain ◽  
Local Variant ◽  
Energy Scaling ◽  
Objective Quality ◽  
Noisy Signals ◽  
Frequency Components ◽  
Ringing Artifact ◽  
Detail Image

This paper develops a detail image signal enhancement that makes images perceived as being clearer and more resolved and so more effective for higher resolution displays. We observe that the local variant signal enhancement makes images more vivid, and the more revealed granular signals harmonically embedded on the local variant signals make images more resolved. Based on this observation, we develop a method that not only emphasizes the local variant signals by scaling up the frequency energy in accordance with human visual perception, but also strengthens the granular signals by embedding the alpha-rooting enhanced frequency components. The proposed energy scaling method emphasizes the detail signals in texture images and rarely boosts noisy signals in plain images. In addition, to avoid the local ringing artifact, the proposed method adjusts the enhancement direction to be parallel to the underlying image signal direction. It was verified through subjective and objective quality evaluations that the developed method makes images perceived as clearer and highly resolved.

scholarly journals DCT-Domain Detail Image Enhancement for More Resolved Images

2021 ◽  
Author(s):  
Seongbae Bang ◽  
Wonha Kim
Keyword(s):  
Signal Enhancement ◽  
Human Visual Perception ◽  
Dct Domain ◽  
Local Variant ◽  
Energy Scaling ◽  
Objective Quality ◽  
Noisy Signals ◽  
Frequency Components ◽  
Ringing Artifact ◽  
Detail Image

This paper develops a detail image signal enhancement that makes images perceived as clearer and more resolved and so is more effective for higher resolution displays. We observe that the local variant signal enhancement makes images more vivid, and the more revealed granular signals harmonically embedded on the local variant signals make images more resolved. Based on this observation, we develop a method that not only emphasizes the local variant signals by scaling up the frequency energy in accordance with human visual perception, but also strengths up the granular signals by embedding the alpha-rooting enhanced frequency components. The proposed energy scaling method emphasizes the detail signals in texture images and rarely boosts noisy signals in plain images. In addition, to avoid the local ringing artifact, the proposed method adjusts the enhancement direction to be parallel to the underlying image signal direction. It was verified through the subjective and objective quality evaluations that the developed method makes images perceived as clearer and highly resolved.

scholarly journals Spatial Filtering in DCT Domain-Based Frameworks for Hyperspectral Imagery Classification

2019 ◽  
Vol 11 (12) ◽  
pp. 1405 ◽  
Author(s):  
Razika Bazine ◽  
Huayi Wu ◽  
Kamel Boukhechba
Keyword(s):  
Hyperspectral Imagery ◽  
Wiener Filter ◽  
Spatial Filtering ◽  
Spatial Filter ◽  
Computational Time ◽  
Support Vector ◽  
Two Dimensional ◽  
Significant Information ◽  
Dct Domain ◽  
Frequency Components

In this article, we propose two effective frameworks for hyperspectral imagery classification based on spatial filtering in Discrete Cosine Transform (DCT) domain. In the proposed approaches, spectral DCT is performed on the hyperspectral image to obtain a spectral profile representation, where the most significant information in the transform domain is concentrated in a few low-frequency components. The high-frequency components that generally represent noisy data are further processed using a spatial filter to extract the remaining useful information. For the spatial filtering step, both two-dimensional DCT (2D-DCT) and two-dimensional adaptive Wiener filter (2D-AWF) are explored. After performing the spatial filter, an inverse spectral DCT is applied on all transformed bands including the filtered bands to obtain the final preprocessed hyperspectral data, which is subsequently fed into a linear Support Vector Machine (SVM) classifier. Experimental results using three hyperspectral datasets show that the proposed framework Cascade Spectral DCT Spatial Wiener Filter (CDCT-WF_SVM) outperforms several state-of-the-art methods in terms of classification accuracy, the sensitivity regarding different sizes of the training samples, and computational time.

Securing Fingerprint Images Through PSO Based Robust Facial Watermarking

2012 ◽  
Vol 6 (2) ◽  
pp. 34-52 ◽  
Author(s):  
Roli Bansal ◽  
Priti Sehgal ◽  
Punam Bedi
Keyword(s):  
Similarity Index ◽  
Image Data ◽  
Structural Similarity ◽  
Facial Image ◽  
Human Visual Perception ◽  
Prediction Ability ◽  
Host Image ◽  
Dct Domain ◽  
Certainty Level ◽  
Watermarking Scheme

Presented is an efficient watermarking scheme using Particle Swarm Optimization (PSO) to watermark host fingerprint images with their corresponding facial images in the Discrete Cosine Transform (DCT) domain. PSO is used to find the best DCT coefficients’ locations in the host image where the facial image data can be embedded, so that the distortion produced in the host image is minimum. The objective function for PSO is formulated in terms of the Structural Similarity Index (SSIM) and the Orientation Certainty Level Index (OCL) so as to base it on the simple visual effect of the human visual perception capability and correct minutia prediction ability. The results exhibit better watermarked image quality while retaining the feature set of the original fingerprint. Moreover, the proposed technique is robust so that the extraction of watermark is possible even after the watermarked image is exposed to attacks. As a result, at the receiver’s end, the watermarked fingerprint image and the extracted facial image can be verified for a secure and accurate biometric based personal authentication.

GA-BASED OPTIMIZATION OF TAPERING WINDOWS FOR ARTIFACT REDUCTION IN FOURIER ELECTRON MAGNETIC RESONANCE IMAGES

2009 ◽  
Vol 08 (02) ◽  
pp. 111-125
Author(s):  
M. SUMATHI ◽  
MURALI C. KRISHNA ◽  
R. MURUGESAN
Keyword(s):  
Magnetic Resonance ◽  
Imaging Modality ◽  
Single Point ◽  
Magnetic Resonance Images ◽  
Electron Magnetic Resonance ◽  
Artifact Reduction ◽  
Conventional Mri ◽  
Window Functions ◽  
Frequency Components ◽  
Ringing Artifact

Optimization of tapering windows for artifact reduction in two-dimensional (2D) Fourier electron magnetic resonance (EMR) tomography using genetic algorithm (GA) is presented. EMR imaging (EMRI) is a fast emerging functional imaging modality for studying free radicals in biological systems. EMRI by single point imaging (SPI) modality is a Fourier imaging technique. The bioclearance of the imaging agent as well as the need to minimize the radio frequency power deposition on the live animals, dictate reduced k-space sampling. This leads to ringing (Gibbs) artifacts in both directions of the 2D image, because, unlike the conventional MRI, SPI is phase encoding in both directions. To dampen the high-frequency components, data tapering windows are multiplicatively applied to provide tolerable blurred resultant image with reduced Gibbs ringing. To find a compromise between blur and ringing artifact, in this paper a method of optimizing the window functions by using GA is proposed. Our experiments suggest GA-based Kaiser window shows better performance by visual as well as quantitative evaluation.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

Feasibility and Clinical Implications of Remotely Guided Ultrasound Examinations

2020 ◽  
Vol 91 (7) ◽  
pp. 592-596
Author(s):  
Quinn Dufurrena ◽  
Kazi Imran Ullah ◽  
Erin Taub ◽  
Connor Leszczuk ◽  
Sahar Ahmad
Keyword(s):  
Clinical Utility ◽  
Regional Wall Motion ◽  
Subjective Assessment ◽  
Clinical Implications ◽  
Pilot Studies ◽  
Objective Quality ◽  
The Us ◽  
Regional Wall Motion Abnormalities ◽  
Wall Motion Abnormalities

BACKGROUND: Remotely guided ultrasound (US) examinations carried out by nonmedical personnel (novices) have been shown to produce clinically useful examinations, at least in small pilot studies. Comparison of the quality of such exams to those carried out by trained medical professionals is lacking in the literature. This study compared the objective quality and clinical utility of cardiac and pulmonary US examinations carried out by novices and trained physicians.METHODS: Cardiac and pulmonary US examinations were carried out by novices under remote guidance by an US expert and independently by US trained physicians. Exams were blindly evaluated by US experts for both a task-based objective score as well as a subjective assessment of clinical utility.RESULTS: Participating in the study were 16 novices and 9 physicians. Novices took longer to complete the US exams (median 641.5 s vs. 256 s). For the objective component, novices scored higher in exams evaluating for pneumothorax (100% vs. 87.5%). For the subjective component, novices more often obtained clinically useful exams in the assessment of cardiac regional wall motion abnormalities (56.3% vs. 11.1%). No other comparisons yielded statistically significant differences between the two groups. Both groups had generally higher scores for pulmonary examinations compared to cardiac. There was variability in the quality of exams carried out by novices depending on their expert guide.CONCLUSION: Remotely guided novices are able to carry out cardiac and pulmonary US examinations with similar, if not better, technical proficiency and clinical utility as US trained physicians, though they take longer to do so.Dufurrena Q, Ullah KI, Taub E, Leszczuk C, Ahmad S. Feasibility and clinical implications of remotely guided ultrasound examinations. Aerosp Med Hum Perform. 2020; 91(7):592–596.

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