Defect detection on transparent or translucent wafers can be performed on a die using references from the same die. A first calculated value based on a kernel size, such as a moving mean, is determined. A first difference is determined by subtracting the first calculated value from a pixel intensity. Candidate pixels with a first difference above a threshold are classified. A second calculated value based on a kernel size, such as a local median, is determined. A second difference is determined by subtracting the second calculated value from the pixel intensity. Pixels that include a defect are classified when the second difference is above the threshold.