Luminosity and contrast enhancement of retinal vessel images using weighted average histogram

2022 ◽  
Vol 71 ◽  
pp. 103089
Author(s):  
Ravi Kumar ◽  
Ashish Kumar Bhandari
Keyword(s):  
Contrast Enhancement ◽  
Weighted Average ◽  
Retinal Vessel

scholarly journals Automatic Tortuosity Estimation of Nerve Fibers and Retinal Vessels in Ophthalmic Images

2020 ◽  
Vol 10 (14) ◽  
pp. 4788
Author(s):  
Honghan Chen ◽  
Bang Chen ◽  
Dan Zhang ◽  
Jiong Zhang ◽  
Jiang Liu ◽  
...  
Keyword(s):  
Nerve Fiber ◽  
Estimation Method ◽  
Weighted Average ◽  
Retinal Vessel ◽  
Ground Truth ◽  
Nerve Fibers ◽  
Public Access ◽  
Close Relationship ◽  
Enhancement Method ◽  
Corneal Nerve

The tortuosity changes of curvilinear anatomical organs such as nerve fibers or vessels have a close relationship with a number of diseases. Therefore, the automatic estimation and representation of the tortuosity is desired in medical image for such organs. In this paper, an automated framework for tortuosity estimation is proposed for corneal nerve and retinal vessel images. First, the weighted local phase tensor-based enhancement method is employed and the curvilinear structure is extracted from raw image. For each curvilinear structure with a different position and orientation, the curvature is measured by the exponential curvature estimation in the 3D space. Then, the tortuosity of an image is calculated as the weighted average of all the curvilinear structures. Our proposed framework has been evaluated on two corneal nerve fiber datasets and one retinal vessel dataset. Experiments on three curvilinear organ datasets demonstrate that our proposed tortuosity estimation method achieves a promising performance compared with other state-of-the-art methods in terms of accuracy and generality. In our nerve fiber dataset, the method achieved overall accuray of 0.820, and 0.734, 0.881 for sensitivity and specificity, respectively. The proposed method also achieved Spearman correlation scores 0.945 and 0.868 correlated with tortuosity grading ground truth for arteries and veins in the retinal vessel dataset. Furthermore, the manual labeled 403 corneal nerve fiber images with different levels of tortuosity, and all of them are also released for public access for further research.

An Energy Analyser for Contrast Enhancement in STEM

1974 ◽  
Vol 32 ◽  
pp. 434-435
Author(s):  
H.T. Pearce-Percy
Keyword(s):  
Contrast Enhancement ◽  
Bending Angle ◽  
Magnetic Sector ◽  
Conventional Design ◽  
Bending Radius ◽  
Sector Type

Recently an energy analyser of the uniform magnetic sector type has been installd in a 100KV microscope. This microscope can be used in the STEM mode. The sector is of conventional design (Fig. 1). The bending angle was chosen to be 90° for ease of construction. The bending radius (ρ) is 20 cm. and the object and image distances are 42.5 cm. and 30.0 cm. respectively.

Positive correlation between neovascularization degree of carotid atherosclerosis determined by contrast-enhanced ultrasound and level of serum C-reactive protein

VASA ◽  
2015 ◽  
Vol 44 (3) ◽  
pp. 0187-0194 ◽  
Author(s):  
Xiaoni Chang ◽  
Jun Feng ◽  
Litao Ruan ◽  
Jing Shang ◽  
Yanqiu Yang ◽  
...  
Keyword(s):  
Contrast Enhancement ◽  
Rank Correlation ◽  
Artery Stenosis ◽  
Contrast Enhanced Ultrasound ◽  
C Reactive Protein ◽  
Protein Levels ◽  
Reactive Protein ◽  
Contrast Enhanced ◽  
Grade 3 ◽  
Axis View

Background: Neovascularization is one of the most important risk factors for unstable plaque. This study was designed to correlate plaque thickness, artery stenosis and levels of serum C-reactive protein with the degree of intraplaque enhancement determined by contrast-enhanced ultrasound. Patients and methods: Contrast-enhanced ultrasound was performed on 72 carotid atherosclerotic plaques in 48 patients. Contrast enhancement within the plaque was categorized as grade 1, 2 or 3. Maximum plaque thickness was measured in short-axis view. Carotid artery stenosis was categorized as mild, moderate or severe. Results: Plaque contrast enhancement was not associated with the degree of artery stenosis or with plaque thickness. Serum C-reactive protein levels were positively correlated with the number of new vessels in the plaque. C-reactive protein levels increased in the three groups(Grade 1: 3.72±1.79mg/L; Grade 2: 7.88±4.24 mg/L; Grade 3: 11.02±3.52 mg/L), with significant differences among them (F=10.14, P<0.01), and significant differences between each two groups (P<0.05). Spearman’s rank correlation analysis showed that serum C-reactive protein levels were positively correlated with the degree of carotid plaque enhancement (Rs =0.69, P<0.01). Conclusions: The combination of C-reactive protein levels and intraplaque neovascularization detected by contrast-enhanced ultrasound may allow more accurate evaluation of plaque stability.

Summer phytoplankton of the northern Barents Sea (75–80º N)

2019 ◽  
pp. 8-19
Author(s):  
Larisa A. Pautova ◽  
Vladimir A. Silkin ◽  
Marina D. Kravchishina ◽  
Valeriy G. Yakubenko ◽  
Anna L. Chultsova
Keyword(s):  
Barents Sea ◽  
Weighted Average ◽  
Arctic Basin ◽  
High Arctic ◽  
Alexandrium Tamarense ◽  
Warm Water ◽  
The Arctic ◽  
Absolute Maximum ◽  
Deep Trench ◽  
Maximum Biomass

The structure of the summer planktonic communities of the Northern part of the Barents sea in the first half of August 2017 were studied. In the sea-ice melting area, the average phytoplankton biomass producing upper 50-meter layer of water reached values levels of eutrophic waters (up to 2.1 g/m3). Phytoplankton was presented by diatoms of the genera Thalassiosira and Eucampia. Maximum biomass recorded at depths of 22–52 m, the absolute maximum biomass community (5,0 g/m3) marked on the horizon of 45 m (station 5558), located at the outlet of the deep trench Franz Victoria near the West coast of the archipelago Franz Josef Land. In ice-free waters, phytoplankton abundance was low, and the weighted average biomass (8.0 mg/m3 – 123.1 mg/m3) corresponded to oligotrophic waters and lower mesotrophic waters. In the upper layers of the water population abundance was dominated by small flagellates and picoplankton from, biomass – Arctic dinoflagellates (Gymnodinium spp.) and cold Atlantic complexes (Gyrodinium lachryma, Alexandrium tamarense, Dinophysis norvegica). The proportion of Atlantic species in phytoplankton reached 75%. The representatives of warm-water Atlantic complex (Emiliania huxleyi, Rhizosolenia hebetata f. semispina, Ceratium horridum) were recorded up to 80º N, as indicators of the penetration of warm Atlantic waters into the Arctic basin. The presence of oceanic Atlantic species as warm-water and cold systems in the high Arctic indicates the strengthening of processes of “atlantificacion” in the region.

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