Retinal Fundus Image Enhancement Using the Normalized Convolution and Noise Removing.

Peishan Dai,Jianmei Zhang,Min Fan,Jing Wu,Hanwei Sheng,Ling Li

doi:10.1155/2016/5075612

Peishan Dai, Jianmei Zhang + Show 4 more

Open Access

https://doi.org/10.1155/2016/5075612

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Abstract

Retinal fundus image plays an important role in the diagnosis of retinal related diseases. The detailed information of the retinal fundus image such as small vessels, microaneurysms, and exudates may be in low contrast, and retinal image enhancement usually gives help to analyze diseases related to retinal fundus image. Current image enhancement methods may lead to artificial boundaries, abrupt changes in color levels, and the loss of image detail. In order to avoid these side effects, a new retinal fundus image enhancement method is proposed. First, the original retinal fundus image was processed by the normalized convolution algorithm with a domain transform to obtain an image with the basic information of the background. Then, the image with the basic information of the background was fused with the original retinal fundus image to obtain an enhanced fundus image. Lastly, the fused image was denoised by a two-stage denoising method including the fourth order PDEs and the relaxed median filter. The retinal image databases, including the DRIVE database, the STARE database, and the DIARETDB1 database, were used to evaluate image enhancement effects. The results show that the method can enhance the retinal fundus image prominently. And, different from some other fundus image enhancement methods, the proposed method can directly enhance color images.

Highlights

Retinal fundus images provide rich information of pathological changes which may indicate diseases such as arteriosclerosis, diabetes, hypertension, stroke, and cardiovascular disease [1]
Different from commonly used image enhancement methods which enhance retinal fundus image directly, the proposed method firstly obtained an image with the basic information of the background through some process of the original image and fused this image with the original image to suppress background to achieve the goal of image enhancement
A retinal image enhancement method fusing original image and the image containing the basic information of the background is presented

Summary

Introduction

Retinal fundus images provide rich information of pathological changes which may indicate diseases such as arteriosclerosis, diabetes, hypertension, stroke, and cardiovascular disease [1]. These images are widely used for diagnosis of related disease. Histogram equalization (HE) [3] is a popular method to improve image contrast, but the decreasing of the gray levels may result in the loss of image details. To overcome this deficiency, contrast limited adaptive histogram equalization (CLAHE) is proposed [4]. Setiawan et al [5]

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Conclusion