Since half the world’s population is at the risk of malaria, it is considered as a serious world health problem. The definite way to diagnose malaria is microscopic observation of blood films. Blood films are techniques in which the position of parasites is fixed on the blood smears. Malaria diagnosis by the microscopic method is a time-consuming and tedious task for technicians. In addition, the wrong decision may be made especially in the early stages of malaria. Some of the problems with manual microscopy can be overcome by exploring computer based methods, which are employed in order to automation of diagnostic procedure. Automatic malaria diagnosis from microscopic images belongs to image kashida; TEXT-ALIGN: justify; LINE-HEIGHT: normal; TEXT-KASHIDA: 0%; MARGIN: 0cm 0cm 0pt; unicode-bidi: embed; DIRECTION: ltr; mso-layout-grid-align: none" Keywords: Automatic malaria diagnosis, nonlinear diffusion filtering, ellipse fitting, least square, circle search