Retinal fundus images play an important role in the diagnosis of Diabetic Retinopathy. The detailed information of retinal images like Retinal Vessels, Exudates and microaneurysms may be in low contrast and retinal image enhancement helps in the accurate diagnosis of retinal images related diseases. This paper proposes a novel contrast enhancement method to make the low-contrast retinal images more qualitative such that the detailed information will be clearer. For this purpose, the proposed mechanism considers the spatial mutual relationships between the gray-levels of image and makes the gray-levels in the output image not only linear to the gray-levels of input image but also related to the neighboring gray-levels. The proposed approach enhances the image both in global and local fashion. Spatial mutual entropy based contrast enhancement is accomplished for global contrast enhancement and Greedy contrast enhancement is accomplished for local contrast enhancement. Extensive simulations carried out over various low-contrast retinal images of High Resolution Fundus (HRF) image database shows the outstanding performance of proposed approach. And, different from some other fundus image enhancement methods, the proposed method can directly enhance color images.
In this paper, the recent advancement in the Digital Image Processing Aspects in the Diabetic Retinopathy (DR) were been discussed. The major approaches in DR are categorized into four classes namely Preprocessing, Optic Disk Detection, Blood Vessel Extraction and supervised classification. The optic disk, blood vessels and exudates gives more analytical details about the retinal image, segmentation of those features are very important. Further these approaches are classified into finer classes based on the methodologies accomplished in the respective schemes. The details of the database those used for testing the proposed algorithms is also illustrated in this paper. The details of performance metrics such as accuracy, sensitivity, specificity, precision, recall and F-measure are also discussed through their mathematical expressions.
Nylon 6,9/CaCu3Ti4O12 (CCTO) nanocrystal composites with relatively high dielectric permittivity (220 at 100 Hz) were fabricated by melt mixing followed by hot pressing. The CCTO nanoceramics were synthesized using the oxalate precursor route, and the transmission electron microscopy studies exhibited that the crystallites are in the range of 20–200 nm. The nanocomposites were characterized using X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and impedance analyzer to study their structural, thermal, and dielectric properties. The introduction of CCTO nanoparticles into the matrix had influenced the thermal properties. The effective dielectric permittivity of the nanocomposite increased by the augmentation of CCTO content in the Nylon 6,9. Our experimental outcomes showed that the fixed dielectric permittivity of such two-phase composite was established above 200 when the CCTO concentration was closer to its percolation threshold. The room temperature dielectric permittivity as high as 220 at 100 Hz has been achieved when the CCTO content increased to 58 vol% in the polymer and this was increased to 3845 at 150°C. The increase in AC conductivity with the increase in the CCTO content in the polymer matrix supported the hopping of the charge carrier conduction mechanism.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.