Figure 3.

Procedure for classifying the retinal images. First, the green channel of the images is selected. Then, the images are processed by AM-FM to decompose them in their AM-FM estimates. Depending on the test, the images are subdivided in ROIs, the macula or the optic disc region is selected, or the entire image without the optic disc is entered into the block of the feature extraction. Features are obtained for each observation. If the image is represented in ROIs, the k-means method is applied; otherwise, the feature selection and the two-step PLS classifier is applied, to obtain the estimated class for each image.