1. A method of inspecting a semiconductor substrate, the method comprising: delivering a beam of electrons to the semiconductor substrate and generating a first image having a plurality of pixels based on electrons emitted from the semiconductor substrate; determining a number of electrons emitted by the semiconductor substrate; determining at least one target region including at least one defect of the semiconductor substrate; and adjusting a gray-scale level of the pixels included in the target region based on the number of received electrons to generate a second image that excludes the at least one defect.