The present study presents a method to quantify lipids, collagen and muscle cells, to help diagnose atherosclerosis using digital image processing techniques. The relative concentrations of these three indicators are crucial in diagnosing atherosclerosis in patients. Digital image processing techniques such as object detection, color enhancement, and shape and texture analysis were used to quantify cells. The objective of the algorithm is to analyze high definition images of coronary arteries and to provide an objective outcome on the atherosclerotic tissue stage. The algorithm presented outstanding results and an innovative method to diagnose atherosclerosis when compared to existing procedures in the literature.