Image Processing Reference
In-Depth Information
1 Introduction
Naturally, the human blood consists of a complex combination of plasma, red blood cells
(RBCs), white blood cells (WBCs), and platelets. Plasma is the fluid component, which con-
tains melted salts and proteins. RBCs make up about 40% of blood volume. WBCs are less, but
greater in size than RBCs. The platelet cells are similar particles, which are smaller than WBCs
and RBCs [ 1 ] .
Anemia occurs when the blood has lower than the normal number of RBCs or insuicient
hemoglobin. RBCs are made inside the spongy marrow of the body's larger bones. Bone mar-
row is always making new RBCs to replace old ones. Normal RBCs die after 120 days in the
bloodstream. Their job is carrying oxygen and removing carbon dioxide (a waste product)
from the body. In addition, RBCs are disk-shaped and move easily through blood vessels, and
they contain an iron-rich protein called hemoglobin. This protein transmits oxygen from the
lungs to the rest of the body [ 1 ]. In sickle-cell anemia, the body makes sickle-shaped RBCs.
Sickle cells contain abnormal hemoglobin called sickle hemoglobin or hemoglobin S, which
contributes to the cells developing a sickle, or crescent, shape. Sickle cells are very dangerous
because of their rigidity and stickiness, which cause the cells to clump, blocking blood flow
in the blood vessels of the limbs and organs. The blocked blood flow can cause pain, organ
damage, and increased probability of infection. Moreover, the abnormal sickle cells usually
die after only about 10-20 days, and the bone marrow cannot make new RBCs fast enough to
replace the dying ones [ 1 ] . Figure 1 illustrates the danger of sickle-cell anemia and its various
FIGURE 1 Kinds of RBCs and sickle-cell anemia.
Sickle-cell anemia is most common in people whose families originate from Mediterranean
countries, Africa, South or Central America (especially Panama and the Caribbean islands),
Saudi Arabia, and India. In the United States of America, approximately 70,000 to 100,000
people suffer from the condition, and they are mainly African Americans. The discovery of
this disease depends on blood test analysis that can specifically detect sickle cells [ 1 ] .
Recently, microscopic-image analysis has been used as an impressive diagnostic tool for de-
tecting irregular blood cells [ 1 ]. The Hough transforms is the most important technique ap-
plied to image analysis and segmentation for the detection of blood cells. The transform de-
pends on extracting features related through the segmentation of the microscopic image. Gen-
erally, the Hough transforms used today were invented by Richard Duda and Peter Hart in
1972, who called it a “generalized Hough transforms” after the related 1962 patent of Paul
Hough [ 2 , 3 ]. Figure 2 shows a simple example of a pixel lying on a definite circle (solid circle),
and the classical circular Hough transform (CHT) voting patern (dashed circles) for the ap-
plicant pixel.
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