A system for autonomously diagnosing a defect in a component to which a penetrant has been applied and at least partially removed for penetrant testing comprises: a device for positioning the component for inspection; a camera configured to take an image of the component when positioned by the device; and a first image evaluation module configured to: process the image of the component with a machine learning algorithm to detect from the image remaining penetrant on the component and based on characteristics of any detected penetrant to provide a first determination of whether or not the image indicates a defect in the component. A corresponding method is also disclosed.