Abstract: From a sample image, a fertilization test method determines the ratio of fertilized cells in the image by identifying cells in the image and calculating cell properties for each cell. An area is determined between a cell body and an outer search limit to search for a fertilization membrane. A cell outline is defined for each cell and cell membrane edges are found within the search area by changing the cell outline size between the cell body boundary the outer search limit, checking for a match with detected cell membrane edges. A cell is determined to be fertilized based on matches between detected cell membrane edges and the cell outline, patterns of contrast changes indicated by a cell membrane, or circles fit to cell membrane edges.