A Bit Plane based Filtering Technique for Drusen in Age-related Macular Degeneration

Objective: The authors propose to develop a new image filter technique based on bit planes of retinal fundus image to enhance the image preprocessing task. Method/Statistical Analysis: The most two significant bit planes of an image are taken and preprocessed using an image matrix filter. The image arithmetic operations are used to enhance the new filter. The sample graded portions of each of the 60 AMD images are processed to study this filter technique. The effect of the technique is studied with basic statistics tests using mean, median, standard deviation and t-test, testing on column vectors of images. Findings: The basic statistic measures such as mean, median, range and standard deviations are applied on image pixel data before and after application of filter technique. The standard deviation of post filtered graded portions of the image shows a higher value than that of the graded portions of unfiltered image, indicating that there is a positive effect of filtering. The effectiveness of the technique is also studied with a statistical paired t-test. This test is used to find the effect of processing bit planes of the respective graded pixel portions in the image samples. This statistical evidence of the result reveal that the null hypothesis is rejected to conclude that image is enhanced for further processing of drusen spots in AMD. Application/Improvements: The least bit planes of the graded portions of the image may be furthur processed to enable easier classification of different types of drusens in the image.