Recognition Of Red Blood Cells Abnormalities Using a New Set of Closed Contour Features

A pixel will be denoted by the symbol xi or xi(m,n), where m represents the horizontal axis and n represents the vertical axis Diagnosis of anemia depends upon the observation of variations in color, shape and gray level distribution inside the Red Blood Cells (RBC's). The most important of all is the variation in the outer contour of an individual cell. In this paper, several new closed contour features are presented, together with some techniques for preprocessing and feature extraction. Preprocessing includes contour extraction and run length coding of a closed contour, while features include concavity, unsymmetry and zero crossing of slope density curve. Features are rotation, transformation and scale invariant in addition to being highly noise tolerant. An efficient design of a decision tree is presented for classification. A continuous contour is defined as a set of points P P = {xi(mi,ni) : |mi-mi+1|<=1, |ni-ni+1|<=1, NOT (ni=nj and mi=mj) for i≠j, i,j=1,..,N } ......(1) A closed contour is defined as the set of points C C = { continuous contour , |mN-m1|<=1, |nN-n1|<=1, NOT (n1=nN and m1=mN) i,j=1,..,N} ......(2) where N = number of points in the contour 3. Preprocessing Preprocessing includes smoothing, thresholding, contour extraction and run-length coding of each individual cell. 1. Abnormalities of Red Blood Cells With the inspection of a large variety of RBC's [13,14], abnormalities were divided into eight major categories: 3.1. Smoothing With reference to [1,2,3], several method for noise reductions exist. Neighborhood averaging is used resulting in an image containing dark cells with light background. Type 1: Normal Shape and Macrocytosis (Biconcave) Type 2: Spherocytosis Type 3: Elliptocytosis Type 4: Tear Drop Shape 3.2. Thresholding Type 5: Cottage Loaf or Helmet Cell Since the histogram of the blood film image is bimodal, iterative thresholding [15] is used. In this method, the threshold Tk+1 is recursively defined as Type 6: Sickle Shape Type 7: Burr Shape or Crenation Type 8: Roleaux and Auto-Agglutination